Tarik Massoud is a Professor of Neuroradiology and Molecular Imaging in the Department of Radiology, Stanford University School of Medicine, where he directs LEMNI (the Laboratory of Experimental and Molecular Neuroimaging), and is an Attending Neuroradiologist in Stanford Health Care. He qualified from the Medical School of the Royal College of Surgeons in Ireland and then served as intern to two inspirational medical giants of their days, Dr. William H. (Willie) Bisset at the Royal Hospital for Sick Children in Edinburgh, UK, and Professor Sir Raymond (Bill) Hoffenberg, PRCP, at the Queen Elizabeth Hospital in Birmingham, UK. He trained in Radiology and Neuroradiology in Oxford, UCLA, and the University of Michigan, and is a Fellow of the Royal College of Radiologists in London. He holds a research MD degree (NUI) in experimental neuroimaging (work conducted at UCLA), and a Cambridge PhD in molecular imaging (work conducted at the Crump Institute for Molecular Imaging at UCLA, and the Molecular Imaging Program at Stanford, Gambhir laboratory). From 2000 to 2013 he was a University Lecturer and Honorary Consultant in Neuroradiology at the University of Cambridge School of Clinical Medicine and Addenbrooke’s Hospital in Cambridge, UK. He was formerly an Assistant and Associate Professor of Radiology at UCLA, and held visiting Associate Professorships at Columbia, New York, and MCW, Milwaukee. He has published extensively and won numerous awards at scientific meetings. His papers in experimental interventional neuroradiology and molecular imaging are widely cited. He has been a peer reviewer for dozens of international medical journals, as well as other medical charities and governmental funding agencies. He is Editor-in-Chief of the journal Reports in Medical Imaging, and an editorial board member for numerous biomedical journals. He is the senior author or editor of several books, including "Glioblastoma: State-of-the-Art Clinical Neuroimaging", "Basilar Artery: A Clinical Review", and "Glioblastoma Resistance to Chemotherapy: Molecular Mechanisms and Innovative Reversal Strategies". In 2016 he was awarded a Special Faculty Permit ('eminent physician license') by the Medical Board of the state of California.

Clinical Focus

  • Neuroradiology
  • Diagnostic Radiology

Academic Appointments

Administrative Appointments

  • Assistant Professor, Neuroradiology, UCLA School of Medicine, Los Angeles (1993 - 1997)
  • Associate Professor, Neuroradiology, UCLA School of Medicine, Los Angeles (1997 - 1999)
  • University Lecturer and Consultant in Neuroradiology, University of Cambridge School of Clinical Medicine and Addenbrooke's Hospital, Cambridge, UK (2000 - 2013)
  • Director, SIMITAR, Stanford Initiative for Multimodality neuro-Imaging in Translational Anatomy Research (SIMITAR) (2019 - Present)
  • Director, Laboratory of Experimental and Molecular Neuroimaging (LEMNI), Molecular Imaging Program at Stanford (MIPS) (2013 - Present)
  • Professor of Radiology (Neuroradiology and Molecular Imaging), Stanford University School of Medicine (2013 - Present)

Honors & Awards

  • Stoney Memorial Gold Medal in Anatomy (Neuroanatomy), Royal College of Surgeons in Ireland (1981)
  • J. J. Fitzsimons Gold Medal and Prize in Surgery, Royal College of Surgeons in Ireland (1984)
  • Kodak Scholar, Royal College of Radiologists, UK (1992)
  • Magna Cum Laude Award for research, American Society of Neuroradiology (1993)
  • William Cook Interventional Fellow, Royal College of Radiologists, UK (1993)
  • Cum Laude Award (on 5 occasions) for research, American Society of Neuroradiology (1994-2001)
  • Magna Cum Laude Award for research, American Society of Neuroradiology (1995)
  • Wormald Grant Award, Royal College of Radiologists, UK (2001)
  • Mid-Career Award for Established Practitioners, The Health Foundation, UK (2002)
  • Special Faculty Permit ('eminent physician license'), Medical Board of California (2016)
  • Guerbet Scientific Cum Laude Award, XXI Symposium Neuroradiologicum (2018)
  • Sigma Xi, nominated and elected member, Sigma Xi (2018)
  • Distinguished Investigator Award, Academy of Radiology and Biomedical Imaging Research (2019)
  • Certificate of Merit Award for education and training, American Society of Neuroradiology (2020)
  • Summa Cum Laude Award for education and training, American Society of Neuroradiology (2020)

Professional Education

  • PhD, University of Cambridge (Emmanuel College), UK, Molecular Imaging and Biology (2007)
  • MD (research doctorate), National University of Ireland, Neuroradiology (2003)
  • MA, University of Cambridge, UK (2003)
  • Fellowship, University of Michigan Medical Center, Ann Arbor, Neuroradiology (clinical) (2000)
  • Fellowship, UCLA Medical Center, Los Angeles, Neuroradiology (research) (1993)
  • FRCR (board certification), Royal College of Radiologists, UK, Radiology (1992)
  • Residency and Fellowship, John Radcliffe Hospital and Radcliffe Infirmary, Oxford, UK, Radiology and Neuroradiology (1992)
  • MB BCh BAO LRCPI&SI, Medical School of the Royal College of Surgeons in Ireland, Dublin, and the National University of Ireland, Medicine (1984)

Current Research and Scholarly Interests

My current interests are in molecular and translational imaging of the brain especially in neuro-oncology and cerebrovascular diseases, experimental aspects of neuroimaging, clinical neuroradiology, neuroradiological anatomy, and research education and academic training of radiologists and scientists.

Clinical Trials

  • 18F-FDOPA PET/CT or PET/MRI in Measuring Tumors in Patients With Newly-Diagnosed or Recurrent Gliomas Not Recruiting

    To evaluate 18F-FDOPA PET obtained from PET/CT or PET/MRI imaging in patients with newly diagnosed or recurrent gliomas.

    Stanford is currently not accepting patients for this trial. For more information, please contact Andrei Iagaru, 650-736-2859.

    View full details

2021-22 Courses

Graduate and Fellowship Programs

  • Neuroradiology (Fellowship Program)

All Publications

  • A Critical Appraisal of Monro's Erroneous Description of the Cerebral Interventricular Foramina: Age-Related MRI Spatial Morphometry and a Proposed New Terminology. Clinical anatomy (New York, N.Y.) Matys, T. n., Brown, F. n., Zaccagna, F. n., Kirollos, R. W., Massoud, T. F. 2020


    Anatomic connections between the cerebral lateral and third ventricles have been mischaracterized since Monro's original erroneous description of his eponymous foramina (FoMs) as being only one T-shaped passage. Accurate knowledge of the in vivo three-dimensional (3D) configuration of FoM has important clinical neuroendoscopic, neurosurgical, and neuroimaging implications. We retrospectively analyzed volumetric high-resolution brain MRIs of 100 normal individuals to characterize the normal spatial anatomy and morphometry for each FoM. We measured the true anatomical 3D angulations of FoMs relative to standard neuroimaging orthogonal planes, and their minimum width, depth, and distance between the medial borders of bilateral FoMs. The right and left FoMs were separate, distinct, and in a V-shaped configuration. Each FoM was a round, oval, or crescent-shaped canal-like passage with well-defined borders formed by the semicircular concavity of the ipsilateral forniceal column. The plane of FoM was angeled on average 56.8° ± 9.1° superiorly from the axial plane, 22.5° ± 10.7° laterally, and 37.0° ± 6.9° anteriorly from the midsagittal plane; all these angles changing significantly with increasing age. The mean narrowest diameter of FoM was 2.8 ± 1.2 mm, and its depth was 2.5 ± 0.2 mm. Thus, the true size and orientation of FoM differs from that depicted on standard neuroimaging. Notably, in young subjects FoM has a diameter smaller than its depth, a configuration akin to a short, small canal. We propose that the eponym "Monro" no longer be associated with this structure, and the term "foramen" be abandoned. Instead, FoM should be more appropriately re-named as the "interventricular canaliculus", or IVC, for short. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23560

    View details for PubMedID 31944414

  • Intranasal delivery of targeted polyfunctional gold-iron oxide nanoparticles loaded with therapeutic microRNAs for combined theranostic multimodality imaging and presensitization of glioblastoma to temozolomide. Biomaterials Sukumar, U. K., Bose, R. J., Malhotra, M., Babikir, H. A., Afjei, R., Robinson, E., Zeng, Y., Chang, E., Habte, F., Sinclair, R., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. 2019; 218: 119342


    The prognosis for glioblastoma (GBM) remains depressingly low. The biological barriers of the brain present a major challenge to achieving adequate drug concentrations for GBM therapy. To address this, we explore the potential of the nose-to-brain direct transport pathway to bypass the blood-brain barrier, and to enable targeted delivery of theranostic polyfunctional gold-iron oxide nanoparticles (polyGIONs) surface loaded with therapeutic miRNAs (miR-100 and antimiR-21) to GBMs in mice. These nanoformulations would thus allow presensitization of GBM cells to the systemically delivered chemotherapy drug temozolomide (TMZ), as well as in vivo multimodality molecular and anatomic imaging of nanoparticle delivery, trafficking, and treatment effects. First, we synthesized GIONs coated with beta-cyclodextrin-chitosan (CD-CS) hybrid polymer, and co-loaded with miR-100 and antimiR-21. Then we decorated their surface with PEG-T7 peptide using CD-adamantane host-guest chemistry. The resultant polyGIONs showed efficient miRNA loading with enhanced serum stability. We characterized them for particle size, PDI, polymer functionalization, charge and release using dynamic light scattering analysis, TEM and qRT-PCR. For in vivo intranasal delivery, we used U87-MG GBM cell-derived orthotopic xenograft models in mice. Intranasal delivery resulted in efficient accumulation of Cy5-miRNAs in mice treated with T7-targeted polyGIONs, as demonstrated by in vivo optical fluorescence and MR imaging. We measured the therapeutic response of these FLUC-EGFP labelled U87-MG GBMs using bioluminescence imaging. Overall, there was a significant increase in survival of mice co-treated with T7-polyGIONs loaded with miR-100/antimiR-21 plus systemic TMZ, compared to the untreated control group, or the animals receiving non-targeted polyGIONs-miR-100/antimiR-21, or TMZ alone. Once translated clinically, this novel theranostic nanoformulation and its associated intranasal delivery strategy will have a strong potential to potentiate the effects of TMZ treatment in GBM patients.

    View details for DOI 10.1016/j.biomaterials.2019.119342

    View details for PubMedID 31326657

  • The protean world of non-coding RNAs in glioblastoma. Journal of molecular medicine (Berlin, Germany) Paulmurugan, R., Malhotra, M., Massoud, T. F. 2019


    Non-coding ribonucleic acids (ncRNAs) are a diverse group of RNA molecules that are mostly not translated into proteins following transcription. We review the role of ncRNAs in the pathobiology of glioblastoma (GBM), and their potential applications for GBM therapy. Significant advances in our understanding of the protean manifestations of ncRNAs have been made, allowing us to better decipher the molecular complexity of GBM. A large number of regulatory ncRNAs appear to have a greater influence on the molecular pathology of GBM than thought previously. Importantly, also, a range of therapeutic approaches are emerging whereby ncRNA-based systems may be used to molecularly target GBM. The most successful of these is RNA interference, and some of these strategies are being evaluated in ongoing clinical trials. However, a number of limitations exist in the clinical translation of ncRNA-based therapeutic systems, such as delivery mechanisms and cytotoxicity; concerted research endeavors are currently underway in an attempt to overcome these. Ongoing and future studies will determine the potential practical role for ncRNA-based therapeutic systems in the clinical management of GBM. These applications may be especially promising, given that current treatment options are limited and prognosis remains poor for this challenging malignancy.

    View details for DOI 10.1007/s00109-019-01798-6

    View details for PubMedID 31129756

  • A protein folding molecular imaging biosensor monitors the effects of drugs that restore mutant p53 structure and its downstream function in glioblastoma cells. Oncotarget Paulmurugan, R., Afjei, R., Sekar, T. V., Babikir, H. A., Massoud, T. F. 2018; 9 (30): 21495–511


    Misfolding mutations in the DNA-binding domain of p53 alter its conformation, affecting the efficiency with which it binds to chromatin to regulate target gene expression and cell cycle checkpoint functions in many cancers, including glioblastoma. Small molecule drugs that recover misfolded p53 structure and function may improve chemotherapy by activating p53-mediated senescence. We constructed and optimized a split Renilla luciferase (RLUC) complementation molecular biosensor (NRLUC-p53-CRLUC) to determine small molecule-meditated folding changes in p53 protein. After initial evaluation of the biosensor in three different cells lines, we engineered endogenously p53P98L mutant (i.e. not affecting the DNA-binding domain) Ln229 glioblastoma cells, to express the biosensor containing one of four different p53 proteins: p53wt, p53Y220C, p53G245S and p53R282W. We evaluated the consequent phenotypic changes in these four variant cells as well as the parental cells after exposure to PhiKan083 and SCH529074, drugs previously reported to activate mutant p53 folding. Specifically, we measured induced RLUC complementation and consequent therapeutic response. Upon stable transduction with the p53 biosensors, we demonstrated that these originally p53P98L Ln229 cells had acquired p53 cellular phenotypes representative of each p53 protein expressed within the biosensor fusion protein. In these engineered variants we found a differential drug response when treated with doxorubicin and temozolomide, either independently or in combination with PhiKan083 or SCH529074. We thus developed a molecular imaging complementation biosensor that mimics endogenous p53 function for use in future applications to screen novel or repurposed drugs that counter the effects of misfolding mutations responsible for oncogenic structural changes in p53.

    View details for PubMedID 29765555

  • Targeted nanoparticle delivery of therapeutic antisense microRNAs presensitizes glioblastoma cells to lower effective doses of temozolomide in vitro and in a mouse model. Oncotarget Malhotra, M., Sekar, T. V., Ananta, J. S., Devulapally, R., Afjei, R., Babikir, H. A., Paulmurugan, R., Massoud, T. F. 2018; 9 (30): 21478–94


    Temozolomide (TMZ) chemotherapy for glioblastoma (GBM) is generally well tolerated at standard doses but it can cause side effects. GBMs overexpress microRNA-21 and microRNA-10b, two known oncomiRs that promote cancer development, progression and resistance to drug treatment. We hypothesized that systemic injection of antisense microRNAs (antagomiR-21 and antagomiR-10b) encapsulated in cRGD-tagged PEG-PLGA nanoparticles would result in high cellular delivery of intact functional antagomiRs, with consequent efficient therapeutic response and increased sensitivity of GBM cells to lower doses of TMZ. We synthesized both targeted and non-targeted nanoparticles, and characterized them for size, surface charge and encapsulation efficiency of antagomiRs. When using targeted nanoparticles in U87MG and Ln229 GBM cells, we showed higher uptake-associated improvement in sensitivity of these cells to lower concentrations of TMZ in medium. Co-inhibition of microRNA-21 and microRNA-10b reduced the number of viable cells and increased cell cycle arrest at G2/M phase upon TMZ treatment. We found a significant increase in expression of key target genes for microRNA-21 and microRNA-10b upon using targeted versus non-targeted nanoparticles. There was also significant reduction in tumor volume when using TMZ after pre-treatment with loaded nanoparticles in human GBM cell xenografts in mice. In vivo targeted nanoparticles plus different doses of TMZ showed a significant therapeutic response even at the lowest dose of TMZ, indicating that preloading cells with antagomiR-21 and antagomiR-10b increases cellular chemosensitivity towards lower TMZ doses. Future clinical applications of this combination therapy may result in improved GBM response by using lower doses of TMZ and reducing nonspecific treatment side effects.

    View details for PubMedID 29765554

  • Restoring guardianship of the genome: Anticancer drug strategies to reverse oncogenic mutant p53 misfolding. Cancer treatment reviews Babikir, H. A., Afjei, R. n., Paulmurugan, R. n., Massoud, T. F. 2018; 71: 19–31


    p53 is a transcription factor that activates numerous genes involved in essential maintenance of genetic stability. P53 is the most frequently mutated gene in human cancer. One third of these mutations are structural, resulting in mutant p53 with a disrupted protein conformation. Here we review current progress in a relatively underexplored aspect of p53-targeted drug development, that is, strategies to reactivate wild-type function of misfolded mutant p53. Unfortunately, most p53-targeted drugs are still at early stages of development and many of them are progressing slowly toward clinical implementation. Significant challenges need to be addressed before clinical translation of new anti-misfolding p53-targeted drugs.

    View details for PubMedID 30336366

  • Tailored Nanoparticle Codelivery of antimiR-21 and antimiR-10b Augments Glioblastoma Cell Kill by Temozolomide: Toward a "Personalized" Anti-microRNA Therapy. Molecular pharmaceutics Ananta, J. S., Paulmurugan, R., Massoud, T. F. 2016; 13 (9): 3164-3175


    Glioblastoma remains an aggressive brain malignancy with poor prognosis despite advances in multimodal therapy that include standard use of Temozolomide. MicroRNA-21 (miR-21) and microRNA-10b (miR-10b) are oncomiRs overexpressed in glioblastoma, promoting many aspects of cancer biology. We hypothesized that PLGA nanoparticles carrying antisense miR-21 (antimiR-21) and antisense miR-10b (antimiR-10b) might beneficially knockdown endogenous miR-21 and miR-10b function and reprogram cells prior to Temozolomide treatment. PLGA nanoparticles were effective in intracellular delivery of encapsulated oligonucleotides. Concentrations of delivered antimiR-21 and antimiR-10b were optimized and specifically tailored to copy numbers of intracellular endogenous microRNAs. Coinhibition of miR-21 and miR-10b significantly reduced the number of viable cells (by 24%; p < 0.01) and increased (2.9-fold) cell cycle arrest at G2/M phase upon Temozolomide treatment in U87 MG cells. Cell-tailored nanoparticle-assisted concurrent silencing of miR-21 and miR-10b prior to Temozolomide treatment is an effective molecular therapeutic strategy in cell culture, warranting the need for further studies prior to future in vivo "personalized" medicine applications.

    View details for DOI 10.1021/acs.molpharmaceut.6b00388

    View details for PubMedID 27508339

  • A molecular imaging biosensor detects in vivo protein folding and misfolding JOURNAL OF MOLECULAR MEDICINE-JMM Sheahan, A. V., Sekar, T. V., Chen, K., Paulmurugan, R., Massoud, T. F. 2016; 94 (7): 799-808


    Aberrant protein folding represents the molecular basis of many important human diseases. Although the discovery of new anti-misfolding drugs is a major priority in molecular therapeutics, there is currently no generalizable protein folding assay for use in cell-based high throughput screening (HTS) of chemical libraries, or for in vivo imaging. We molecularly engineered a bioluminescence-based biosensor composed of rationally split Firefly luciferase reporter fragments flanking a test protein, and used this in a protein-fragment complementation assay to quantitatively measure folding of the test protein. We comprehensively validated this biosensor in vitro, in cells, and by optically imaging protein folding and misfolding in living mice using several test proteins including enhanced green fluorescent protein, Renilla luciferase, Gaussia luciferase, and SIRT1. Applications of this novel biosensor are potentially far-reaching in both cell-based HTS approaches to discover new anti-misfolding drugs, and when using the same biosensor in validation studies of drug candidates in small animal models.Novel anti-misfolding drugs are needed as molecular therapeutics for many diseases. We developed first in vivo imaging protein folding biosensor to aid drug discovery. Biosensor created by flanking a test protein with rationally split Firefly luciferase. Biosensor validated by detecting folding of test proteins EGFP, Rluc, Gluc, and SIRT1. Generalizable molecular biosensor for translational applications in drug screening.

    View details for DOI 10.1007/s00109-016-1437-9

    View details for PubMedID 27277823

  • Temozolomide-loaded PLGA nanoparticles to treat glioblastoma cells: a biophysical and cell culture evaluation NEUROLOGICAL RESEARCH Ananta, J. S., Paulmurugan, R., Massoud, T. F. 2016; 38 (1): 51-59


    Current chemotherapies for brain glioblastoma do not achieve sufficient drug concentrations within tumors. Polymeric nanoparticles have useful physicochemical properties that make them promising as nanoparticle platforms for glioblastoma drug delivery. Poly[lactic-co-glycolic acid] (PLGA) nanoparticles encapsulating temozolomide (TMZ) could improve localized delivery and sustained drug release to glioblastomas.We investigated three different procedures to encapsulate TMZ within PLGA nanoparticles. We studied the biophysical features of optimized nanocarriers, including their size, shape, surface properties, and release characteristics of TMZ. We evaluated the antiproliferative and cytotoxic effects of TMZ-loaded PLGA nanoparticles on U87 MG glioblastoma cells.A single emulsion technique using a TMZ saturated aqueous phase produced nanoparticles ≤200 nm in size allowing a maximal drug loading of 4.4% w/w of polymer. There was a bi-phasic drug release pattern, with 80% of TMZ released within the first 6 h. Nanoparticles accumulated in the cytoplasm after effective endocytosis. There was no significant difference in cytotoxic effect of TMZ encapsulated within PLGA nanoparticles and free TMZ.PLGA nanoparticles are not suitable as carriers of TMZ for glioblastoma drug delivery on account of the overall high IC50 values of glioblastoma cells to TMZ and poor loading and encapsulation efficiencies. Further biotechnological developments aimed at improving the loading of TMZ in PLGA nanoparticles or co-delivery of small molecule sensitizers to improve the response of human glioblastoma cells to TMZ are required for this approach to be considered and optimized for future clinical translation.

    View details for DOI 10.1080/01616412.2015.1133025

    View details for PubMedID 26905383

  • Nanoparticle-Delivered Antisense MicroRNA-21 Enhances the Effects of Temozolomide on Glioblastoma Cells MOLECULAR PHARMACEUTICS Ananta, J. S., Paulmurugan, R., Massoud, T. F. 2015; 12 (12): 4509-4517


    Glioblastoma (GBM) generally exhibits high IC50 values for its standard drug treatment, temozolomide (TMZ). MicroRNA-21 (miR-21) is an oncomiR overexpressed in GBM, thus controlling important aspects of glioma biology. We hypothesized that PLGA nanoparticles carrying antisense miR-21 to glioblastoma cells might beneficially knock down endogenous miR-21 prior to TMZ treatment. PLGA nanoparticles encapsulating antisense miR-21 were effective in intracellular delivery and sustained silencing (p < 0.01) of miR-21 function in U87 MG, LN229, and T98G cells. Prior antisense miR-21 delivery significantly reduced the number of viable cells (p < 0.001), and increased (1.6-fold) cell cycle arrest at G2/M phase upon TMZ treatment in U87 MG cells. There was overexpression of the miR-21 target genes PTEN (by 67%) and caspase-3 (by 15%) upon cotreatment. This promising PLGA nanoparticle-based platform for antisense miR-21 delivery to GBM is an effective cotherapeutic strategy in cell culture, warranting the need for further studies prior to future clinical translation.

    View details for DOI 10.1021/acs.molpharmaceut.5b00694

    View details for PubMedID 26559642

  • Transvenous Retrograde Nidus Sclerotherapy Under Controlled Hypotension (TRENSH): Hemodynamic Analysis and Concept Validation in a Pig Arteriovenous Malformation Model NEUROSURGERY Massoud, T. F. 2013; 73 (2): 332-343


    BACKGROUND:: Transvenous retrograde nidus sclerotherapy under controlled hypotension (TRENSH) is a proposed novel concept for endovascular treatment of cerebral arteriovenous malformations (AVMs). OBJECTIVE:: To assess the experimental hemodynamic feasibility of TRENSH in a pig AVM model. METHODS:: We surgically constructed carotid-jugular fistula-type AVM models in eight pigs. In five pigs (Group 1) we hemodynamically assessed the AVM through the main arterial feeder (AF) and draining vein (DV) at systemic normotension (Systnorm). We then performed retrograde nidus angiography through the DV at progressively deeper levels of hemorrhagic systemic hypotension (Systhypo), and graded and correlated these angiograms with the degree of Systhypo. In another three pigs (Group 2) we correlated the effects of temporary balloon occlusion of the main AF with the angiographic extent of retrograde nidus filling. RESULTS:: In Group 1 pigs, the drop in AF pressure correlated strongly (r=0.93-0.99) with the drop in DV pressure at progressively deeper Systhypo. Minimal retrograde nidus filling occurred at Systnorm. We observed progressively greater extents of retrograde nidus filling as the transnidal pressure gradients fell with deeper Systhypo. Near-complete retrograde permeation of the nidus was possible as the transnidal gradients approached zero mmHg. As more of the nidus filled, its concurrent emptying was documented through a greater number of DVs. Temporary AF occlusion resulted in improved retrograde nidus filling in all Group 2 pigs. CONCLUSION:: Endovascular TRENSH appears feasible in a pig AVM model. Further experimental investigations of TRENSH are necessary to assess its full potential prior to future clinical applications.

    View details for DOI 10.1227/01.neu.0000430765.80102.77

    View details for Web of Science ID 000330383100050

    View details for PubMedID 23670033

  • A molecularly engineered split reporter for imaging protein-protein interactions with positron emission tomography NATURE MEDICINE Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2010; 16 (8): 921-U123


    Improved techniques to noninvasively image protein-protein interactions (PPIs) are essential. We molecularly engineered a positron emission tomography (PET)-based split reporter (herpes simplex virus type 1 thymidine kinase), cleaved between Thr265 and Ala266, and used this in a protein-fragment complementation assay (PCA) to quantify PPIs in mammalian cells and to microPET image them in living mice. An introduced point mutation (V119C) markedly enhanced thymidine kinase complementation in PCAs, on the basis of rapamycin modulation of FKBP12-rapamycin-binding domain (FRB) and FKBP12 (FK506 binding protein), the interaction of hypoxia-inducible factor-1alpha with the von Hippel-Lindau tumor suppressor, and in an estrogen receptor intramolecular protein folding assay. Applications of this unique split thymidine kinase are potentially far reaching, including, for example, considerably more accurate monitoring of immune and stem cell therapies, allowing for fully quantitative and tomographic PET localization of PPIs in preclinical small- and large-animal models of disease.

    View details for DOI 10.1038/nm.2185

    View details for Web of Science ID 000280649200033

    View details for PubMedID 20639890

    View details for PubMedCentralID PMC2917476

  • Noninvasive molecular neuroimaging using reporter genes: Part II, experimental, current, and future applications AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Singh, A., Gambhir, S. S. 2008; 29 (3): 409-418


    In this second article, we review the various strategies and applications that make use of reporter genes for molecular imaging of the brain in living subjects. These approaches are emerging as valuable tools for monitoring gene expression in diverse applications in laboratory animals, including the study of gene-targeted and trafficking cells, gene therapies, transgenic animals, and more complex molecular interactions within the central nervous system. Further development of more sensitive and selective reporters, combined with improvements in detection technology, will consolidate the position of in vivo reporter gene imaging as a versatile technique for greater understanding of intracellular biologic processes and underlying molecular neuropathology and will potentially establish a future role in the clinical management of patients with neurologic diseases.

    View details for DOI 10.3174/ajnr.A0863

    View details for Web of Science ID 000254066700002

    View details for PubMedID 18272565

  • Noninvasive molecular neuroimaging using reporter genes: Part I, principles revisited AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Singh, A., Gambhir, S. S. 2008; 29 (2): 229-234


    In this first article, we review the basic principles of using reporter genes for molecular imaging of the brain in living subjects. This approach is emerging as a valuable tool for monitoring gene expression in diverse applications in laboratory animals, including the study of gene-targeted and trafficking cells, gene therapies, transgenic animals, and more complex molecular interactions within the central nervous system. Further development of more sensitive and selective reporters, combined with improvements in detection technology, will consolidate the position of in vivo reporter gene imaging as a versatile method for greater understanding of intracellular biologic processes and underlying molecular neuropathology and will potentially establish a future role in the clinical management of patients with neurologic diseases.

    View details for DOI 10.3174/ajnr.A0864

    View details for Web of Science ID 000253345200011

    View details for PubMedID 18024575

  • Integrating noninvasive molecular imaging into molecular medicine: an evolving paradigm TRENDS IN MOLECULAR MEDICINE Massoud, T. F., Gambhir, S. S. 2007; 13 (5): 183-191


    Molecular imaging is a rapidly emerging field, providing noninvasive visual quantitative representations of fundamental biological processes in intact living subjects. Fundamental biomedical research stands to benefit considerably from advances in molecular imaging, with improved molecular target selection, probe development and imaging instrumentation. The noninvasiveness of molecular imaging technologies will also provide benefit through improved patient care. Molecular imaging endpoints can be quantified, and therefore are particularly useful for translational research. Integration of the two disciplines of molecular imaging and molecular medicine, combined with systems-biology approaches to understanding disease complexity, promises to provide predictive, preventative and personalized medicine that will transform healthcare.

    View details for DOI 10.1016/j.molmed.2007.03.003

    View details for Web of Science ID 000247166100002

    View details for PubMedID 17403616

  • Reporter gene imaging of protein-protein interactions in living subjects CURRENT OPINION IN BIOTECHNOLOGY Massoud, T. F., Paulmurugan, R., De, A., Ray, P., Garnbhir, S. S. 2007; 18 (1): 31-37


    In the past few years there has been a veritable explosion in the field of reporter gene imaging, with the aim of determining the location, duration and extent of gene expression within living subjects. An important application of this approach is the molecular imaging of interacting protein partners, which could pave the way to functional proteomics in living animals and might provide a tool for the whole-body evaluation of new pharmaceuticals targeted to modulate protein-protein interactions. Three general methods are currently available for imaging protein-protein interactions in living subjects using reporter genes: a modified mammalian two-hybrid system, a bioluminescence resonance energy transfer (BRET) system, and split reporter protein complementation and reconstitution strategies. In the future, these innovative approaches are likely to enhance our appreciation of entire biological pathway systems and their pharmacological regulation.

    View details for DOI 10.1016/j.copbio.2007.01.007

    View details for Web of Science ID 000244593000006

    View details for PubMedID 17254764

  • Molecular imaging of homodimeric protein-protein interactions in living subjects. FASEB journal Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2004; 18 (10): 1105-1107


    Homodimeric protein interactions are potent regulators of cellular functions, but are particularly challenging to study in vivo. We used a split synthetic renilla luciferase (hRLUC) complementation-based bioluminescence assay to study homodimerization of herpes simplex virus type 1 thymidine kinase (TK) in mammalian cells and in living mice. We quantified and imaged homodimerization of TK chimeras containing N-terminal (N-hRLUC) or C-terminal (C-hRLUC) fragments of hRLUC in the upstream and downstream positions, respectively (tail-to-head homodimer). This was monitored using luminometry (68-fold increase, and was significantly [P<0.01] above background light emission) and by CCD camera imaging of living mice implanted with ex vivo transfected 293T cells (2.7-fold increase, and is significantly [P<0.01] above background light emission). We also made a mutant-TK to generate N-hRLUC mutant TK and mutant TK-C-hRLUC by changing a single amino acid at position 318 from arginine to cysteine, a key site that has previously been reported to be essential for TK homo-dimerization, to support the specificity of the hRLUC complementation signal from TK homodimerization. Ex vivo substrate (8-3H Penciclovir) accumulation assays in 293T cells expressing the TK protein chimeras showed active TK enzyme. We also devised an experimental strategy by constructing variant TK chimeras (possessing extra N-hRLUC or C-hRLUC 'spacers') to monitor incremental lack of association of the tail-to-head TK homodimer. Application of this potentially generalizable assay to screen for molecules that promote or disrupt ubiquitous homodimeric protein-protein interactions could serve not only as an invaluable tool to understand biological networks but could also be applied to drug discovery and validation in living subjects.

    View details for PubMedID 15132989

  • Molecular imaging in living subjects: seeing fundamental biological processes in a new light GENES & DEVELOPMENT Massoud, T. F., Gambhir, S. S. 2003; 17 (5): 545-580

    View details for DOI 10.1101/gad.1047403

    View details for Web of Science ID 000181502300001

    View details for PubMedID 12629038

  • Laboratory evaluation of a microangioscope for potential percutaneous cerebrovascular applications AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Murayama, Y., Vinuela, F., Utsumi, A. 2001; 22 (2): 363-365


    A laboratory-based study of the physical and performance characteristics of a new 0.25-mm-thin microangioscope was performed. The microangioscope tested was compatible with currently available microcatheters, but its tip was considerably stiff and of limited radiopacity. Poor image quality and difficult image interpretation were further drawbacks. Intensive efforts are directed at addressing current limitations and testing further innovations that could pave the way for future performance in neurovascular endoscopy.

    View details for Web of Science ID 000167049300027

    View details for PubMedID 11156784

  • Experimental radiosurgery simulations using a theoretical model of cerebral arteriovenous malformations STROKE Massoud, T. F., Hademenos, G. J., De Salles, A. A., Solberg, T. D. 2000; 31 (10): 2466-2476


    A novel biomathematical arteriovenous malformation (AVM) model based on electric network analysis was used to investigate theoretically the potential role of intranidal hemodynamic perturbations in elevating the risk of rupture after simulated brain AVM radiosurgery.The effects of radiation on 28 interconnected plexiform and fistulous AVM nidus vessels were simulated by predefined random or stepwise occlusion. Electric circuit analysis revealed the changes in intranidal flow, pressure, and risk of rupture at intervals of 3 months during a 3-year latency period after simulated partial/complete irradiation of the nidus using doses <25 and >/=25 Gy. An expression for risk of rupture was derived on the basis of the functional distribution of the critical radii of component vessels. The theoretical effects of radiation were also tested on AVM nidus vessels with progressively increasing elastic modulus (E:) and wall thickness during the latency period, simulating their eventual fibrosis.In an AVM with E=5. 0x10(4) dyne/cm(2), 4 (14.3%) of a total 28 sets of AVM radiosurgery simulations revealed theoretical nidus rupture (risk of rupture >/=100%). Three of these were associated with partial nidus coverage and 1 with complete treatment. All ruptures occurred after random occlusion of nidus vessels in AVMs receiving low-dose radiosurgery. Intranidal hemodynamic perturbations were observed in all cases of AVM rupture; the occlusion of a fistulous component resulted in intranidal rerouting of flow and escalation of the intravascular pressure in adjacent plexiform components. Risk of rupture was found to correlate with nidus vessel wall strength: a low E: of 1.9x10(4) dyne/cm(2) resulted in a 92.8% incidence of AVM rupture, whereas a higher E: of 7.0x10(4) dyne/cm(2) resulted in only a 3.6% incidence of AVM rupture. A dramatic reduction in rupture incidence was observed when increasing fibrosis of the nidus was modeled during the latency period.It was found that the theoretical occurrence of AVM hemorrhage after radiosurgery was low, particularly when radiation-induced fibrosis of nidus vessels was considered. When rupture does occur, it would appear from a theoretical standpoint that the occlusion of intranidal fistulas or larger-caliber plexiform vessels could be a significant culprit in the generation of critical intranidal hemodynamic surges resulting in nidus rupture. The described AVM model should serve as a useful research tool for further theoretical investigations of cerebral AVM radiosurgery and its hemodynamic sequelae.

    View details for Web of Science ID 000089655900033

    View details for PubMedID 11022081

  • Histopathologic characteristics of a chronic arteriovenous malformation in a swine model: Preliminary study AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Vinters, H. V., CHAO, K. H., Vinuela, F., Jahan, R. 2000; 21 (7): 1268-1276


    The experimental induction of histologic transformations in microvessels of similar caliber to those of nidus vessels of cerebral arteriovenous malformations (AVMs) has not been attempted previously. Our goal was to examine preliminarily the histopathologic characteristics of nidus vessels and the angiographic features of a chronic AVM model in swine.AVM models were fashioned from bilateral carotid retia mirabilia of seven swine after the surgical formation of large unilateral carotid-jugular fistulas. One AVM model was made for immediate use, whereas in the other six, follow-up angiography was obtained at varying intervals (2 to 180 days) after model creation. Light and electron microscopy, immunohistochemistry (using monoclonal antibodies against smooth muscle actin and PC10 against proliferating cell nuclear antigen), and histometry were performed on the nidus vessels of three swine: one acutely created, one 2 months old, and one 6 months old.Vascular dilatation and tortuosity of the main arterial feeder and draining vein were evident angiographically as early as 4 days after AVM creation, and were maximal in the 6-month-old model. Compared with the acutely created nidus vessels, those in the two chronic models revealed disrupted and attenuated elastica and intimal hyperplasia that was focal ("cushions") or generalized, leading to luminal occlusion. Variable numbers of cells in the tunica media of chronic nidus vessels contained smooth muscle actin. PC10/proliferating cell nuclear antigen immunoreactivity was observed in the endothelium and subendothelial layers. Histometry showed increases in intimal hyperplasia and medial thickness in the chronic vessels.Nidus vessels in this chronic swine AVM model exhibited striking histologic changes similar to those seen in cerebral AVMs. The induced vessel growth seen angiographically and histologically in components of the chronic AVMs was consistent with the presence of persistently raised intravascular hemodynamic loads. This preliminary feasibility study suggests that the realistic histologic characteristics of this chronic AVM model are an attractive feature, and if confirmed in future, more comprehensive, studies would be of benefit in accurate histopathologic interpretation of the effects of superimposed experimental embolotherapy or radiosurgery. This model may provide a useful experimental tool to study the dynamic cellular and tissue events that dictate the development and natural history of AVMs.

    View details for Web of Science ID 000165054800018

    View details for PubMedID 10954279

  • Can induction of systemic hypotension help prevent nidus rupture complicating arteriovenous malformation embolization?: analysis of underlying mechanisms achieved using a theoretical model AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Hademenos, G. J., Young, W. L., Gao, E. H., Pile-Spellman, J. 2000; 21 (7): 1255-1267


    Nidus rupture is a serious complication of intracranial arteriovenous malformation (AVM) embolotherapy, but its pathogenetic mechanisms are not well described. An AVM model based on electrical network analysis was used to investigate theoretically the potential role of hemodynamic perturbations for elevating the risk of nidus vessel rupture (Rrupt) after simulated AVM embolotherapy, and to assess the potential benefit of systemic hypotension for preventing rupture.Five separate hypothetical mechanisms for nidus hemorrhage were studied: 1) intranidal rerouting of blood pressure; 2) extranidal rerouting of blood pressure; 3) occlusion of draining veins with glue; 4) delayed thrombosis of draining veins; and 5) excessively high injection pressures proximal to the nidus. Simulated occlusion of vessels or elevated injection pressures were implemented into the AVM model, and electrical circuit analysis revealed the consequent changes in intranidal flow, pressure, and Rrupt for the nidus vessels. An expression for Rrupt was derived based on the functional distribution of the critical radii of component vessels. If AVM rupture was observed (Rrupt > or = 100%) at systemic normotension (mean pressure [P] = 74 mm Hg), the theoretical embolization was repeated under systemic hypotension (minor P = 70 mm Hg, moderate P = 50 mm Hg, or profound P = 25 mm Hg) to assess the potential benefit of this maneuver in reducing hemorrhage rates.All five pathogenetic mechanisms under investigation were able to produce rupture of AVMs during or after embolotherapy. These different mechanisms had in common the capability of generating surges in intranidal hemodynamic parameters resulting in nidus vessel rupture. The theoretical induction of systemic hypotension during and after treatment was shown to be of significant benefit in attenuating these surges and reducing Rrupt to safer levels below 100%.The induction of systemic hypotension during and after AVM embolization would appear theoretically to be of potential use in preventing iatrogenic nidus hemorrhage. The described AVM model should serve as a useful research tool for further theoretical investigations of AVM embolotherapy and its hemodynamic sequelae.

    View details for Web of Science ID 000165054800017

    View details for PubMedID 10954278

  • Transvenous retrograde nidus sclerotherapy under controlled hypotension (TRENSH): A newly proposed treatment for brain arteriovenous malformations-concepts and rationale NEUROSURGERY Massoud, T. F., Hademenos, G. J. 1999; 45 (2): 351-363


    An alternative endovascular treatment to conventional transarterial embolization of cerebral arteriovenous malformations (AVMs) is proposed.According to this proposed treatment, selected AVMs could undergo transvenous retrograde nidus sclerotherapy under controlled hypotensive anesthesia (TRENSH).It is hypothesized that TRENSH may provide the means of avoiding delivery of embolic agents via arterial feeders (thus preventing ischemic complications), in addition to a possible more complete permeation of an AVM nidus with a sclerosant than can otherwise be obtained with current agents via arterial feeders.Instead of relying on access to an AVM nidus from the arterial side (with its usual complexity), TRENSH would require retrograde access to the lesion via much larger and anatomically simpler draining veins. Retrograde permeation of the AVM nidus may then be possible with a liquid sclerosant (to effect a "chemical embolization") provided that the arterial inflow is reduced sufficiently by temporary controlled systemic hypotension, with or without the aid of temporary balloon occlusion of the main arterial feeder(s). Retrograde spread of sclerosant within the nidus that falls short of filling arterial feeders and their branches to normal brain tissue may then be possible. Angioarchitectural and hemodynamic considerations are addressed, as are the potential role and limitations of TRENSH in the management of cerebral pial AVMs. Future implementation of this new technique in some specific selected cases in which the anatomic configuration of the AVM and its draining veins might be favorable could prove to be a potentially useful addition to the armamentarium of AVM therapies, which currently includes microsurgery, radiosurgery, and transarterial embolotherapy. Experimental studies directed at assessing the feasibility of TRENSH before potential future clinical application seem justified.

    View details for Web of Science ID 000081906200034

    View details for PubMedID 10449081

  • Principles and philosophy of modeling in biomedical research FASEB JOURNAL Massoud, T. F., Hademenos, G. J., Young, W. L., Gao, E. Z., Pile-Spellman, J., Vinuela, F. 1998; 12 (3): 275-285


    Despite widespread applications in biomedical research, the role of models and modeling is often controversial and ill understood. It is usual to find that fundamental definitions, axioms, and postulates used in the modeling process have become tacit assumptions. What is essential, however, is a clear vision of the fundamental principles of modeling. This is even more compelling for new and emerging interdisciplinary fields that use techniques from previously separate scientific disciplines. This article outlines and reviews the central nature and philosophy of modeling, the rules that govern it, and its underlying key integral relationship to the 'scientific method'. A comprehensive understanding of these issues is indispensable to successful research and meaningful progress in all facets of biomedicine.

    View details for Web of Science ID 000072305500016

    View details for PubMedID 9580086

  • A Clinical PET Imaging Tracer ([18F]DASA-23) to Monitor Pyruvate Kinase M2 Induced Glycolytic Reprogramming in Glioblastoma. Clinical cancer research : an official journal of the American Association for Cancer Research Beinat, C., Patel, C. B., Haywood, T., Murty, S., Naya, L., Castillo, J. B., Reyes, S. T., Phillips, M., Buccino, P., Shen, B., Park, J. H., Koran, M. E., Alam, I. S., James, M. L., Holley, D., Halbert, K., Gandhi, H., He, J. Q., Granucci, M., Johnson, E., Liu, D. D., Uchida, N., Sinha, R., Chu, P., Born, D. E., Warnock, G. I., Weissman, I., Hayden Gephart, M., Khalighi, M. M., Massoud, T. F., Iagaru, A., Davidzon, G., Thomas, R., Nagpal, S., Recht, L. D., Gambhir, S. S. 2021


    PURPOSE: Pyruvate kinase M2 (PKM2) catalyzes the final step in glycolysis, a key process of cancer metabolism. PKM2 is preferentially expressed by glioblastoma (GBM) cells with minimal expression in healthy brain. We describe the development, validation, and translation of a novel positron emission tomography (PET) tracer to study PKM2 in GBM. We evaluated 1-((2-fluoro-6-[18F]fluorophenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine ([18F]DASA-23) in cell culture, mouse models of GBM, healthy human volunteers, and GBM patients.EXPERIMENTAL DESIGN: [18F]DASA-23 was synthesized with a molar activity of 100.47 {plus minus} 29.58 GBq/mol and radiochemical purity >95%. We performed initial testing of [18F]DASA-23 in GBM cell culture and human GBM xenografts implanted orthotopically into mice. Next we produced [18F]DASA-23 under FDA oversight, and evaluated it in healthy volunteers, and a pilot cohort of glioma patients.RESULTS: In mouse imaging studies, [18F]DASA-23 clearly delineated the U87 GBM from surrounding healthy brain tissue and had a tumor-to-brain ratio (TBR) of 3.6 {plus minus} 0.5. In human volunteers, [18F]DASA-23 crossed the intact blood-brain barrier and was rapidly cleared. In GBM patients, [18F]DASA-23 successfully outlined tumors visible on contrast-enhanced magnetic resonance imaging (MRI). The uptake of [18F]DASA-23 was markedly elevated in GBMs compared to normal brain, and it identified a metabolic non-responder within 1-week of treatment initiation.CONCLUSIONS: We developed and translated [18F]DASA-23 as a new tracer that demonstrated the visualization of aberrantly expressed PKM2 for the first time in human subjects. These results warrant further clinical evaluation of [18F]DASA-23 to assess its utility for imaging therapy-induced normalization of aberrant cancer metabolism.

    View details for DOI 10.1158/1078-0432.CCR-21-0544

    View details for PubMedID 34475101

  • Camouflaged Hybrid Cancer Cell-Platelet Fusion Membrane Nanovesicles Deliver Therapeutic MicroRNAs to Presensitize Triple-Negative Breast Cancer to Doxorubicin ADVANCED FUNCTIONAL MATERIALS Liu, Y., Sukumar, U. K., Kanada, M., Krishnan, A., Massoud, T. F., Paulmurugan, R. 2021
  • Imaging and treatment of brain tumors through molecular targeting: Recent clinical advances. European journal of radiology Zaccagna, F., Grist, J. T., Quartuccio, N., Riemer, F., Fraioli, F., Caraco, C., Halsey, R., Aldalilah, Y., Cunningham, C. H., Massoud, T. F., Aloj, L., Gallagher, F. A. 2021; 142: 109842


    Molecular imaging techniques have rapidly progressed over recent decades providing unprecedented in vivo characterization of metabolic pathways and molecular biomarkers. Many of these new techniques have been successfully applied in the field of neuro-oncological imaging to probe tumor biology. Targeting specific signaling or metabolic pathways could help to address several unmet clinical needs that hamper the management of patients with brain tumors. This review aims to provide an overview of the recent advances in brain tumor imaging using molecular targeting with positron emission tomography and magnetic resonance imaging, as well as the role in patient management and possible therapeutic implications.

    View details for DOI 10.1016/j.ejrad.2021.109842

    View details for PubMedID 34274843

  • Editorial: Advanced Neuroimaging of Brain Metastases FRONTIERS IN NEUROLOGY Vachha, B. A., Huang, S. Y., Massoud, T. F. 2021; 12
  • Ultrasound Triggered Co-Delivery of Therapeutic MicroRNAs and a Triple Suicide Gene Therapy Vector by Using Biocompatible Polymer Nanoparticles for Improved Cancer Therapy in Mouse Models ADVANCED THERAPEUTICS Kumar, S., Wang, H., Telichko, A. V., Natarajan, A., Bettinger, T., Cherkaoui, S., Massoud, T. F., Dahl, J. J., Paulmurugan, R. 2021
  • Editorial: Advanced Neuroimaging of Brain Metastases. Frontiers in neurology Vachha, B. A., Huang, S. Y., Massoud, T. F. 2021; 12: 668310

    View details for DOI 10.3389/fneur.2021.668310

    View details for PubMedID 33815266

    View details for PubMedCentralID PMC8010233

  • High-Throughput Whole-Plate Imaging of Cells for Multiple Biological Applications. Methods in molecular biology (Clifton, N.J.) Sukumar, U. K., Habte, F., Massoud, T. F., Paulmurugan, R. 2021; 2274: 367-384


    Advanced multipurpose cell imaging systems along with integrated rapid quantitation software can enhance and expedite cancer cell culture studies in a variety of applications. Though accurate cell culture studies are an important and necessary component of nearly all cancer biomarker detection and therapy studies, the methods we currently use are of low-throughput, time consuming, and lack accuracy. Hence, it is important to improve several features of the assays to increase the accuracy of their quantitative outputs in most studies. In general, we perform cell culture analysis semimanually by counting a small aliquot of suspended cells using a hemocytometer or viewing a small area of cells on a plate using a bright-field microscope, and then extrapolate the counts or observations to estimate the values for the total numbers of cells. The fundamental problem with this process lies in using techniques, such as extrapolation, which inherently introduces intrasample variability while collecting the cells by enzymatic trypsinization for these assays that are affecting cell growth and other downstream assessments. Fluorescence (FL) microscopy-based assays are also used to image and count cells for various applications, including cell viability, proliferation, apoptosis, cell death, transfection efficiency, protein expression, stem cell properties, colony formation, cytotoxicity, drug dose-response, and treatment efficacy studies. These methods are not optimal for many researches, as they require real-time visualization under a microscope plus manual analysis to determine the final results. Owing to long exposure times for cells under fluorescent light of a microscope, the cells may be exposed to suboptimal conditions that affect cell growth, and with occasional photobleaching of the expressed FL probes. Alternatively, the use of cell imaging systems that integrate both advanced bright-field and FL imaging for cell counting and quantification can be useful. In this protocol, we discuss the advantages of a high-throughput cell imaging system using a whole-plate imaging format when used in various bioimaging studies by highlighting a few applications of the system. The system is designed to fundamentally improve the accuracy and time of cell culture analysis while also allowing us to perform the assay without trypsinization, thus avoiding the need to replicate multiple wells for monitoring cell growth over time.

    View details for DOI 10.1007/978-1-0716-1258-3_30

    View details for PubMedID 34050486

  • Ambiguous "Olfactory" Terms for Anatomic Spaces Adjacent to the Cribriform Plate: A Publication Database Analysis and Quest for Uniformity. Clinical anatomy (New York, N.Y.) Bates, N. S., Massoud, T. F. 2021


    A precise nomenclature and terminology is the foundation of communication in Anatomy and related biomedical sciences. The olfactory bulbs and nerves lie above and below the cribriform plate (CP), respectively. Hence, many anatomical landmarks in this region have names adopting the term "olfactory" as qualifiers. Ambiguous use of these "olfactory" terms exists, with some potential repercussions on patient treatments. We performed a publication database analysis to determine the frequency of misuse of names for five anatomical "olfactory" spaces close to the CP and nasal cavity. We searched PubMed® publications having the keyword "olfactory" in their title or abstract, plus one of seven other keywords: "groove", "fossa", "recess", "cleft", "vestibule", "sulcus" and "cistern". We reviewed all abstracts for accuracy of these terms relative to accepted norms or customary definitions. By February 2020, we found all these keywords in 1255 articles. For the terms olfactory "groove" and "fossa", the number of relevant articles (and percentage of those inaccurately using these terms) were 374 (1.1%), and 49 (8.2%), respectively. All 52 abstracts containing "olfactory" and "vestibule" were irrelevant, relating to the "nasal vestibule" and olfactory function, instead of "olfactory vestibule". Overall, terms used to describe "olfactory" spaces near the CP are seldom ambiguous or inaccurate, but the terms olfactory "groove" and "fossa" are occasionally misused, We propose several new "olfactory" terms for inclusion in the Terminologia Anatomica, and stress the need for uniform nomenclature leading to greater consistency and accuracy in clinical use of anatomical terms containing the word "olfactory" as a descriptor. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23771

    View details for PubMedID 34370888

  • SARS-CoV-2 Vaccine Development: An Overview and Perspectives. ACS pharmacology & translational science Liu, Y., Wang, K., Massoud, T. F., Paulmurugan, R. 2020; 3 (5): 844–58


    Coronavirus disease 2019, abbreviated as COVID-19, is caused by a new strain of coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It started in late December 2019 in Wuhan, China, and by mid-March 2020, the disease had spread globally. As of July 17, 2020, this pandemic virus has infected 13.9 million people and claimed the life of approximately 593 000 people globally, and the numbers continue to climb. An unprecedented effort is underway to develop therapeutic and prophylactic strategies against this disease. Various drugs and vaccines are undergoing rapid development, and some of these are already in phase III clinical trials. Although Russia was the first to release a vaccine by skipping phase III clinical trials, there is no evidence of large-scale clinical trials, and the safety and efficacy of the vaccine are still a concern. Nevertheless, critical lessons can be learned and data garnered for developing promising vaccines against this rapidly emerging virus or other similar pathogens in the future. In this overview, we cover the available information on the various vaccine development initiatives by different companies, the potential strategies adopted for vaccine design, and the challenges and clinical impact expected from these vaccines. We also briefly discuss the possible role of these vaccines and the specific concerns for their use in patients with pre-existing disease conditions such as cardiovascular, lung, kidney, and liver diseases, cancer patients who are receiving immunosuppressive medications, including anticancer chemotherapies, and many other sensitive populations, such as children and the elderly.

    View details for DOI 10.1021/acsptsci.0c00109

    View details for PubMedID 33062951

  • Predicting tumour mutational burden from histopathological images using multiscale deep learning NATURE MACHINE INTELLIGENCE Jain, M. S., Massoud, T. F. 2020; 2 (6): 356–62
  • Ossification of the pterygoalar and pterygospinous ligaments: a computed tomography analysis of infratemporal fossa anatomical variants relevant to percutaneous trigeminal rhizotomy JOURNAL OF NEUROSURGERY Matys, T., Ali, T., Zaccagna, F., Barone, D. G., Kirollos, R. W., Massoud, T. F. 2020; 132 (6): 1942–51
  • Imaging Anatomy of the Vertebral Canal for Trans-Sacral Hiatus Puncture of the Lumbar Cistern. Clinical anatomy (New York, N.Y.) Trinh, A., Hashmi, S. S., Massoud, T. F. 2020


    A standard lumbar puncture may be impossible for many anatomic or technical reasons. Previous accounts of caudal epidural anesthesia and other procedures via the sacral hiatus prompted us to test if image-guided percutaneous trans-sacral hiatus access to the lumbosacral subarachnoid cistern would be anatomically feasible. To study vertebral canal morphometry and curvature, we analyzed midsagittal CT-myelogram images of 40 normal subjects and digitally measured sacral curvatures between S1 to S5 and S2 to S4 using two methods whereby a lower angle signifies a straighter sacrum. We measured midsagittal vertebral canal area, hiatus width, dural sac termination levels, and distance from sacral hiatus to the dural sac tip (needle distance). Subjects were F:M=25:15, with a mean age of 44.9years. The two S1-S5 full sacral curvature mean angles were 57.3° and 60.4°. Almost all sacral hiatuses were at S4, and dural sac terminations were at S1-S2. The mean S2-S4 sacral curvature was 25.1°, and the mean needle distance was 57.7mm. Using two-way ANOVA, there were significant sex differences for needle distances (p=.001), and full and limited sacral curvatures (p=.02, and p=.046, respectively). There were no significant linear regression correlations between age and sacral curvature, needle distance, canal area, or hiatus width. Therefore, despite a frequently prominent full sacral curvature, the combination of S1-S2 dural sac termination plus a relatively straight trajectory of the lower vertebral canal between S2 and S4 support the theoretical feasibility of percutaneous trans-sacral hiatus and vertebral canal access to the lumbosacral cistern using a standard spinal needle. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23612

    View details for PubMedID 32323367

  • The Mammillothalamic Tracts: Age-Related Conspicuity and Normative Morphometry on Brain Magnetic Resonance Imaging. Clinical anatomy (New York, N.Y.) Niri, S. G., Khalaf, A. M., Massoud, T. F. 2020


    The mammillothalamic tract (MTT, bundle of Vicq d'Azyr) is a white-matter projection from each mammillary body to the anterior nucleus of the thalamus (ANT). Deep brain stimulation of the MTTs or ANTs is a treatment option for medically refractory focal epilepsy. Since the ANTs may be atrophied in epilepsy, targeting of the MTT terminations could be used as a proxy for ANT locations. However, MTT conspicuity and morphometry on MRI have not been evaluated to date. We investigated normative age- and sex-related MRI morphometrics of the MTTs in healthy individuals. We retrospectively analysed magnified axial T2-weighted images of 80 subjects for bilateral MTT conspicuity, diameters, areas, shapes, precise locations, and symmetry. We statistically tested the effects of independent variables (sex and MTT side) on measured dependent variables using two-way ANOVA; and performed linear regressions with age as the independent variable for each of the dependent variables. Subjects were F:M=44:36, with mean age 45.3years. Only one (0.63%) MTT was inconspicuous. Mean MTT diameter was 1.8mm, area was 2.0mm2 , and distance from third ventricle was 3.1mm. MTTs were mostly bilaterally symmetrical in shape, equally round or ovoid. The right MTT diameter was larger than the left, and males had larger MTT areas than females. We found no statistical difference between MTT diameters and areas in young, middle-aged, and older adults. We report normative axial MRI morphometrics of the MTTs to guide neuromodulation treatments. Future detailed analyses will determine if the MTTs atrophy in proportion to the ANTs in refractory epilepsy.

    View details for DOI 10.1002/ca.23595

    View details for PubMedID 32239548

  • Highly sensitive eight-channel light sensing system for biomedical applications. Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology Kim, S. B., Hori, S. S., Sadeghipour, N., Sukumar, U. K., Fujii, R., Massoud, T. F., Paulmurugan, R. 2020


    We demonstrate the potential of an eight-channel light sensing platform system, named Black Box I (BBI), for rapid and highly sensitive measurement of low-level light using a nonradioactive optical readout. We developed, normalized, and characterized the photon sensitivities of the eight channels of the BBI using placental alkaline phosphatase (PLAP) as a model imaging reporter. We found that the BBI system had a statistically strong linear correlation with the reference IVIS Lumina II system. When we applied normalization constants, we were able to optimize the photomultiplier tubes (PMT) of all eight channels of the BBI (up to r2 = 0.998). We investigated the biomedical utilities of BBI by: (i) determining alkaline phosphatase activities in mouse plasma samples as a diagnostic secretory biomarker of cancer, and (ii) diagnosing cancer metastases in the organs of mice bearing triple negative breast cancer. We provide an important new addition to low-cost biomedical instruments intended for pre-clinical diagnostic imaging with high sensitivity, high sample throughput, portability, and rapid on-site analysis of low-level light.

    View details for DOI 10.1039/d0pp00017e

    View details for PubMedID 32159572

  • SP94-Targeted Triblock Copolymer Nanoparticle Delivers Thymidine Kinase-p53-Nitroreductase Triple Therapeutic Gene and Restores Anticancer Function against Hepatocellular Carcinoma in Vivo. ACS applied materials & interfaces Sukumar, U. K., Rajendran, J. C., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. 2020


    Gene-directed enzyme-prodrug therapy (GDEPT) is a promising approach for cancer therapy, but it suffers from poor targeted delivery in vivo. Polyethylenimine (PEI) is a cationic polymer efficient in delivering negatively charged nucleic acids across cell membranes; however, it is highly toxic in vivo. Hence, we efficiently reduced PEI toxicity without compromising its transfection efficiency by conjugating it with poly(d,l-lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) as triblock copolymers through a multistep synthetic process. The synthesized nanoparticles showed efficient delivery of loaded nucleic acids to tumor cells in vitro and in vivo in mice. We used this nanoparticle to deliver a rationally engineered thymidine kinase (TK)-p53-nitroreductase (NTR) triple therapeutic gene against hepatocellular carcinoma (HCC), where p53 tumor suppressor gene is mutated in more than 85% of cancers. TK-p53-NTR triple gene therapy restores p53 function and potentiates cancer cell response to delivered prodrugs (ganciclovir (GCV) and CB1954). We used SP94 peptide-functionalized PLGA-PEG-PEI nanoparticles for the optimal delivery of TK-p53-NTR therapeutic gene in vivo. The nanoparticles prepared from the conjugated polymer showed high loading efficiency for the DNA and markedly enhanced TK-NTR-mediated gene therapy upon the simultaneous coexpression of p53 by the concurrent rescue of the endogenous apoptotic pathway in HCC cells of both p53-mutant and wild-type phenotypes in vitro. In vivo delivery of TK-p53-NTR genes by SP94-targeted PLGA-PEG-PEI NP in mice resulted in a strong expression of suicide genes selectively in tumors, and subsequent administration of GCV and CB1954 led to a decline in tumor growth, and established a superior therapeutic outcome against HCC. We demonstrate a highly efficient approach that exogenously supplements p53 to enable synergy with the outcome of TK-NTR suicide gene therapy against HCC.

    View details for DOI 10.1021/acsami.9b20071

    View details for PubMedID 32048820

  • Tortuosity of Superior Cerebral Veins: Comparative MRI Morphometrics in Normal Subjects and Arteriovenous Malformation Patients. Clinical anatomy (New York, N.Y.) Telischak, N. A., Yedavalli, V. n., Massoud, T. F. 2020


    Blood vessel tortuosity results from increased diameter and length in response to higher hemodynamic loads. Tortuosity metrics have not been determined for abnormal superior cerebral veins (SCVs) draining cerebral arteriovenous malformations (AVM). Draining vein (DV) tortuosity may influence safety and efficacy of retrograde microcatheter navigation during transvenous treatment of pial AVMs. Here we quantify SCV tortuosity in normal subjects and AVM patients using two image segmentation methods. We used contrast-enhanced brain magnetic resonance images to define the axis of each SCV through a regularly spaced set of 3D points defining its skeleton curve. We then calculated two metrics: the 'sum of angles metric' (SOAM), which adds all angles of curvature along a vessel and normalizes by vessel length, and the 'distance metric' (DM), a tortuosity measure providing a ratio of vessel length to linear distance between vessel endpoints. We analyzed 168 metrics in 43 veins of eight normal subjects and 41 veins of seven AVM patients. In normal subjects, the mean SOAM and DM for SCVs were 21.34±7.49 and 1.42±0.25 degrees/mm, respectively. In AVM patients, DVs had a significantly higher mean SOAM of 30.43±11.38 (P=0.02) and DM of 2.79±1.77 (P=0.01) degrees/mm than normal subjects. In AVM patients, DVs were significantly more tortuous than matched contralateral uninvolved SCVs, which were similar in tortuosity to normal subject SCVs. We thus report normative tortuosity metrics of brain SCVs, and show that AVM cortical DVs are significantly more tortuous than normal SCVs. Knowledge of these comparative tortuosities is valuable in planning endovenous AVM embolotherapies. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23589

    View details for PubMedID 32196753

  • Reconstructed Apoptotic Bodies as Targeted "Nano Decoys" to Treat Intracellular Bacterial Infections within Macrophages and Cancer Cells. ACS nano Bose, R. J., Tharmalingam, N. n., Garcia Marques, F. J., Sukumar, U. K., Natarajan, A. n., Zeng, Y. n., Robinson, E. n., Bermudez, A. n., Chang, E. n., Habte, F. n., Pitteri, S. J., McCarthy, J. R., Gambhir, S. S., Massoud, T. F., Mylonakis, E. n., Paulmurugan, R. n. 2020


    Staphylococcus aureus (S. aureus) is a highly pathogenic facultative anaerobe that in some instances resides as an intracellular bacterium within macrophages and cancer cells. This pathogen can establish secondary infection foci, resulting in recurrent systemic infections that are difficult to treat using systemic antibiotics. Here, we use reconstructed apoptotic bodies (ReApoBds) derived from cancer cells as "nano decoys" to deliver vancomycin intracellularly to kill S. aureus by targeting inherent "eat me" signaling of ApoBds. We prepared ReApoBds from different cancer cells (SKBR3, MDA-MB-231, HepG2, U87-MG, and LN229) and used them for vancomycin delivery. Physicochemical characterization showed ReApoBds size ranges from 80 to 150 nm and vancomycin encapsulation efficiency of 60 ± 2.56%. We demonstrate that the loaded vancomycin was able to kill intracellular S. aureus efficiently in an in vitro model of S. aureus infected RAW-264.7 macrophage cells, and U87-MG (p53-wt) and LN229 (p53-mt) cancer cells, compared to free-vancomycin treatment (P < 0.001). The vancomycin loaded ReApoBds treatment in S. aureus infected macrophages showed a two-log-order higher CFU reduction than the free-vancomycin treatment group. In vivo studies revealed that ReApoBds can specifically target macrophages and cancer cells. Vancomycin loaded ReApoBds have the potential to kill intracellular S. aureus infection in vivo in macrophages and cancer cells.

    View details for DOI 10.1021/acsnano.0c00921

    View details for PubMedID 32347709

  • Magnetic Resonance Imaging Anatomy and Morphometry of Lumbar Intervertebral Foramina to Guide Safe Transforaminal Subarachnoid Punctures. Clinical anatomy (New York, N.Y.) Khalaf, A. M., Yedavalli, V., Massoud, T. F. 2019


    Percutaneous transforaminal lumbar punctures (TFLPs) offer alternative access routes to the lumbar subarachnoid cistern. Safe fluoroscopic insertion of a needle through a lumbar intervertebral foramen (IVF) should ideally avoid the exiting spinal nerve and surrounding vascular pedicles. A crescentic region in the posterior aspect of IVF is the conventional position for needle placement during TFLP, but the underlying anatomic basis for this has not been evaluated fully. To enhance TFLP safety, we defined the morphometry of normal lumbar IVFs and precise locations of neurovascular structures in the IVF posterior crescent. We retrospectively reviewed high-resolution T2-weighted lumbar spine magnetic resonance images of 40 normal adults to establish normative dimensions of each IVF from L1 to L5 bilaterally. We segmented the IVF posterior crescent into three parts, and within each, measured the areas occupied by neurovascular structures. We statistically correlated the presence or absence of neurovascular structures in each crescent segment using a Chi-square test. The mean morphometrics for all 304 IVFs in 10 males and 30 females of similar ages were: area 115.3±29.5mm2 ; height 18.0±2.4mm; and width at mid-disc level 5.6±2.1mm. We found a significant association between crescent segment and presence or absence of neurovascular structures (chi2 =95.9, p<0.001). A post-hoc calculation of adjusted standardized residuals identified a significant association between the middle crescent segment and absence of neurovascular structures. Thus, the middle segment of the IVF posterior crescent is significantly most devoid of neurovascular structures, and more often would be the safest target for needle placement during TFLP. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23533

    View details for PubMedID 31837183

  • Three-Dimensional Angles of Confluence of Cortical Bridging Veins and the Superior Sagittal Sinus on MR Venography: Does Drainage of Adjacent Brain Arteriovenous Malformations Alter this Spatial Configuration? Clinical anatomy (New York, N.Y.) Yedavalli, V., Telischak, N. A., Jain, M. S., Massoud, T. F. 2019


    Few neuroimaging anatomic studies to date have investigated in detail the point of entry of cortical bridging veins (CBVs) into the superior sagittal sinus (SSS). Although we know that most CBVs join the SSS at an acute angle opposite to the direction of SSS blood flow, the three-dimensional (3-D) spatial configuration of these venous confluences has not been studied previously. This anatomical information would be pertinent to several clinically applicable scenarios, such as in planning intracranial surgical approaches that preserve bridging veins; studying anatomical factors in the pathophysiology of SSS thrombosis; and when planning endovascular microcatheterization of pial veins to retrogradely embolize brain arteriovenous malformations (AVMs). We used the concept of Euclidean planes in 3-D space to calculate the arccosine of these CBV-SSS angles of confluence. To test the hypothesis that pial AVM draining veins may not be any more acutely angled or difficult to microcatheterize at the SSS than for normal CBVs, we measured 70 angles of confluence on magnetic resonance venography images of 11 normal, and nine AVM patients. There was no statistical difference between normal and AVM patients in the CBV-SSS angles projected in 3-D space (56.2° [SD=22.4°], and 46.2° [SD=22.3°], respectively; P >0.05). Hence, participation of CBVs in drainage of pial AVMs should not confer any added difficulty to their microcatheterization across the SSS, when compared to the acute angles found in normal individuals. This has useful implications for potential choices of strategies requiring endovascular transvenous retrograde approaches to treat AVMs. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23521

    View details for PubMedID 31749197

  • Optic Chiasm Morphometric Changes in Multiple Sclerosis: Feasibility of a Simplified Brain MRI Measure of White Matter Atrophy. Clinical anatomy (New York, N.Y.) Zaccagna, F., Matys, T., Massoud, T. F. 2019


    Sophisticated volume measurements of brain structures on MRI may improve specificity in determining long-term progression of multiple sclerosis (MS), but these techniques are laborious. The optic chiasm (OC) is a white matter (WM) structure clearly visible on routine MRI and is related to the optic nerves (ONs), which are known to atrophy in MS. We hypothesized that OC morphometric measurements would show OC atrophy in MS compared to normal patients. If so, this could help establish a novel simplified brain MRI measure of WM atrophy in MS patients. We retrospectively evaluated standard brain MRIs of 97 patients with known MS, and 98 normal individuals. We electronically measured eight OC morphometrics on axial T2WIs and midsagittal T1WIs: OC width and antero-posterior (AP) diameter, diameters of each ON and optic tract (OT), and angles between the ONs or OTs. Mean OC width, AP diameter and height in MS patients were 11.83±1.25mm (95%CI 11.58-12.09), 2.99±0.65mm (95%CI 2.85-3.12), and 2.09±0.37mm (95%CI 2-2.19), respectively. In normal individuals they were 12.1±1.4mm (95%CI 11.78-12.34), 3.43±0.63mm (95%CI 3.3-3.58), and 2.15±0.37mm (95%CI 2.07-2.23), respectively. There were statistically significant differences between MS patients and controls for AP diameter (p=0.000), but not for width (p=0.204) or height (p=0.183). The ONs were significantly smaller in MS (p<0.0017), but not the OTs. Thus, the OC is significantly atrophied in an unstratified cohort of MS patients. Future studies may establish an MRI OC morphometric index to evaluate demyelinating disease in the brain. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/ca.23446

    View details for PubMedID 31381196

  • Are high lumbar punctures safe? A magnetic resonance imaging morphometric study of the conus medullaris CLINICAL ANATOMY Yedavalli, V., Jain, M. S., Das, D., Massoud, T. F. 2019; 32 (5): 618–29

    View details for DOI 10.1002/ca.23359

    View details for Web of Science ID 000469935300003

  • Molecular Imaging of Retinoic Acids in Live Cells Using Single-Chain Bioluminescence Probes ACS COMBINATORIAL SCIENCE Kim, S., Fujj, R., Nishihara, R., Bose, R. C., Citterio, D., Suzuki, K., Massoud, T. F., Paulmurugan, R. 2019; 21 (6): 473–81
  • Are High Lumbar Punctures Safe? An MRI Morphometric Study of the Conus Medullaris. Clinical anatomy (New York, N.Y.) Yedavalli, V., Jain, M. S., Das, D., Massoud, T. F. 2019


    A high lumbar puncture (LP) at L2-L3 or above is often necessary to consider on technical grounds, but complications of conus medullaris (CM) damage during high LP are potentially concerning. We hypothesized that a high LP might be safer than previously thought, by accounting for movements of the CM upon patient positional changes. We retrospectively reviewed standard normal supine lumbar spine MRIs of 58 patients, and used electronic calipers on axial images at the T12-L1, L1-2, and L2-3 disc levels to measure the transverse diameter of the CM relative to the size of the dorsal thecal sac space (DTSS) through which a spinal needle could be inserted. On 142 axial images, the means for CM diameters were 8.2 mm, 6.0 mm, and 2.9 mm at the three levels, respectively. We then used known literature mean CM displacement values in the legs flexed and unflexed lateral decubitus positions (LDP), to factor in CM shifts to the dependent side. We found that at all three levels, the likely positional shift of the CM would be too small and insufficient to displace the entire CM out of the DTSS. However, if needle placement could be confined to the midsagittal plane, an LP in the unflexed LDP would theoretically be entirely safe at both L1-L2 and L2-L3, and almost so at L2-L3 in the legs flexed LDP. Thus, high LPs at L1-L2 and L2-3 are in theory likely safer than considered previously, more so in the legs unflexed than in the flexed LDP. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30807670

  • Molecular Imaging of Retinoic Acids in Live Cells Using Single-Chain Bioluminescence Probes. ACS combinatorial science Kim, S. B., Fujii, R. n., Nishihara, R. n., Bose, R. J., Citterio, D. n., Suzuki, K. n., Massoud, T. F., Paulmurugan, R. n. 2019


    Retinoic acid (RA) is a key metabolite necessary for embryonic development and differentiation in vertebrates. We demonstrate the utility of genetically encoded, ligand-activatable single-chain bioluminescence probes for detecting RAs from different biological sources. We examined 13 different molecular designs to identify an efficient single-chain probe that can quantify RA with significant sensitivity. The optimal probe consisted of four components: the N- and C-terminal fragments of artificial luciferase variant-16 (ALuc16), the ligand binding domain of retinoic acid receptor α (RARα LBD), and an LXXLL interaction motif. This probe showed a 5.2-fold greater bioluminescence intensity in response to RA when compared to the vehicle control in live mammalian cells. The probe was highly selective to all-trans-RA (at-RA), and highly sensitive in determining at-RA levels in cells derived from tumor xenografts created using MDA-MB-231 cells engineered to stably express the probe. We also detected RA levels in serum and cerebrospinal fluid. Using this probe, the detection limit for at-RA was ∼10-9.5 M, with a linear range of two orders. We present a highly useful technique to quantitatively image endogenous at-RA levels in live mammalian cells expressing novel single-chain bioluminescence probes.

    View details for PubMedID 31034200

  • Ligand-activated BRET9 imaging for measuring protein-protein interactions in living mice. Chemical communications (Cambridge, England) Bae Kim, S. n., Fujii, R. n., Natarajan, A. n., Massoud, T. F., Paulmurugan, R. n. 2019


    Bioluminescence resonance energy transfer (BRET) is a commonly used assay system for studying protein-protein interactions and protein folding in vivo. Conventional BRET systems have solely depended on an overlap of the energy donor and acceptor spectra. In this study, we engineered a conceptually unique ligand-activatable BRET system (termed BRET9), where a full-length Artificial Luciferase variant 23 (ALuc23), acting as the energy donor, is sandwiched between a protein pair of interest, FRB and FKBP12, and linked to a fluorescent protein as the energy acceptor. A specific ligand, rapamycin, then activates inter- and intramolecular interactions of FRB and FKBP12, which develop molecular strain in the sandwiched ALuc23 to accelerate further folding. We found that this system greatly enhanced both the total bioluminescence spectrum and the BRET signal in the far-red (FR) region. We characterized the molecular construct by studying 18 different designs categorized into four groups. The best BRET system design allowed an approximately 5-fold enhancement of the bioluminescence intensities in the FR region. This new BRET system provides a robust ligand-activatable platform that efficiently reports FR bioluminescence signals in cells and living animal models.

    View details for DOI 10.1039/c9cc07634d

    View details for PubMedID 31807738

  • Large-scale ensemble simulations of biomathematical brain arteriovenous malformation models using graphics processing unit computation. Computers in biology and medicine Jain, M. S., Do, H. M., Wintermark, M. n., Massoud, T. F. 2019; 113: 103416


    Theoretical modeling allows investigations of cerebral arteriovenous malformation (AVM) hemodynamics, but current models are too simple and not clinically representative. We developed a more realistic AVM model based on graphics processing unit (GPU) computing, to replicate highly variable and complex nidus angioarchitectures with vessel counts in the thousands-orders of magnitude greater than current models.We constructed a theoretical electrical circuit AVM model with a nidus described by a stochastic block model (SBM) of 57 nodes and an average of 1000 plexiform and fistulous vessels. We sampled and individually simulated 10,000 distinct nidus morphologies from this SBM, constituting an ensemble simulation. We assigned appropriate biophysical values to all model vessels, and known values of mean intravascular pressure (Pmean) to extranidal vessels. We then used network analysis to calculate Pmean and volumetric flow rate within each nidus vessel, and mapped these values onto a graphic representation of the nidus network. We derived an expression for nidus rupture risk and conducted a model parameter sensitivity analysis.Simulations revealed a total intranidal volumetric blood flow ranging from 268 mL/min to 535 mL/min, with an average of 463 mL/min. The maximum percentage rupture risk among all vessels in the nidus ranged from 0% to 60%, with an average of 29%.This easy to implement biomathematical AVM model, allowed by parallel data processing using advanced GPU computing, will serve as a useful tool for theoretical investigations of AVM therapies and their hemodynamic sequelae.

    View details for DOI 10.1016/j.compbiomed.2019.103416

    View details for PubMedID 31494430

  • Eponymous "valves" of the nasolacrimal drainage apparatus. I. A historical review CLINICAL ANATOMY Yedavalli, V., Das, D., Massoud, T. F. 2019; 32 (1): 41–45

    View details for DOI 10.1002/ca.23284

    View details for Web of Science ID 000454304400008

  • Eponymous "valves" of the nasolacrimal drainage apparatus. II. Frequency of visualization on dacryocystography CLINICAL ANATOMY Yedavalli, V., Das, D., Massoud, T. F. 2019; 32 (1): 35–40

    View details for DOI 10.1002/ca.23283

    View details for Web of Science ID 000454304400007

  • Computational Network Modeling of Intranidal Hemodynamic Compartmentalization in a Theoretical Three-Dimensional Brain Arteriovenous Malformation. Frontiers in physiology Jain, M. S., Do, H. M., Massoud, T. F. 2019; 10: 1250


    There are currently no in vivo techniques to accurately study dynamic equilibrium of blood flow within separate regions (compartments) of a large brain arteriovenous malformation (AVM) nidus. A greater understanding of this AVM compartmentalization, even if theoretical, would be useful for optimal planning of endovascular and multimodal AVM therapies. We aimed to develop a biomathematical AVM model for theoretical investigations of intranidal regions of increased mean intravascular pressure (Pmean) and flow representing hemodynamic compartments, upon simulated AVM superselective angiography (SSA). We constructed an AVM model as a theoretical electrical circuit containing four arterial feeders (AF1-AF4) and a three-dimensional nidus of 97 interconnected plexiform and fistulous components. We simulated SSA by increases in Pmean in each AF (with and without occlusion of all other AFs), and then used network analysis to establish resulting increases in Pmean and flow within each nidus vessel. We analyzed shifts in hemodynamic compartments consequent to increasing AF injection pressures. SSA simulated by increases of 10 mm Hg in AF1, AF2, AF3, or AF4 resulted in dissipation of Pmean over 38, 66, 76, or 20% of the nidus, respectively, rising slightly with simultaneous occlusion of other AFs. We qualitatively analyzed shifting intranidal compartments consequent to varying injection pressures by mapping the hemodynamic changes onto the nidus network. Differences in extent of nidus filling upon SSA injections provide theoretical evidence that hemodynamic and angioarchitectural features help establish AVM nidus compartmentalization. This model based on a theoretical AVM will serve as a useful computational tool for further investigations of AVM embolotherapy strategies.

    View details for DOI 10.3389/fphys.2019.01250

    View details for PubMedID 31607956

    View details for PubMedCentralID PMC6769414

  • Ossification of the pterygoalar and pterygospinous ligaments: a computed tomography analysis of infratemporal fossa anatomical variants relevant to percutaneous trigeminal rhizotomy. Journal of neurosurgery Matys, T. n., Ali, T. n., Zaccagna, F. n., Barone, D. G., Kirollos, R. W., Massoud, T. F. 2019: 1–10


    OBJECTIVEOssification of pterygoalar and pterygospinous ligaments traversing the superior aspect of the infratemporal fossa results in formation of osseous bars that can obstruct percutaneous needle access to the trigeminal ganglion through the foramen ovale (FO), interfere with lateral mandibular nerve block, and impede transzygomatic surgical approaches. Presence of these ligaments has been studied on dry skulls, but description of their radiological anatomy is scarce, in particular on cross-sectional imaging. The aim of this study was to describe visualization of pterygoalar and pterygospinous bars on computed tomography (CT) and to review their prevalence and clinical significance.METHODSThe authors retrospectively reviewed 200 helical sinonasal CT scans by analyzing 0.75- to 1.0-mm axial images, maximum intensity projection (MIP) reconstructions, and volume rendered (VR) images, including views along the anticipated axis of the needle in percutaneous Hartel and submandibular approaches to the FO.RESULTSOssified pterygoalar and pterygospinous ligaments were readily identifiable on CT scans. An ossified pterygoalar ligament was demonstrated in 10 patients, including 1 individual with bilateral complete ossification (0.5%), 4 patients with unilateral complete ossification (2.0%), and 5 with incomplete unilateral ossification (2.5%). Nearly all patients with pterygoalar bars were male (90%, p < 0.01). An ossified pterygospinous ligament was seen in 35 patients, including 2 individuals with bilateral complete (1.0%), 8 with unilateral complete (4%), 8 with bilateral incomplete (4.0%), 12 with bilateral incomplete (6.0%) ossification, and 5 (2.5%) with mixed ossification (complete on one side and incomplete on the contralateral side). All pterygoalar bars interfered with a hypothetical needle access to the FO using the Hartel approach but not the submandibular approach. In contrast, 54% of complete and 24% of incomplete pterygospinous bars impeded the submandibular approach to the FO, without affecting the Hartel approach.CONCLUSIONSThis study provides the first detailed description of cross-sectional radiological and applied surgical anatomy of pterygoalar and pterygospinous bars. Our data are clinically useful during skull base imaging to predict potential obstacles to percutaneous cannulation of the FO and assist in the choice of approach, as these two variants differentially impede the Hartel and submandibular access routes. Our results can also be useful in planning surgical approaches to the skull base through the infratemporal fossa.

    View details for PubMedID 31075780

  • Restoring guardianship of the genome: Anticancer drug strategies to reverse oncogenic mutant p53 misfolding CANCER TREATMENT REVIEWS Babikir, H. A., Afjei, R., Paulmurugan, R., Massoud, T. F. 2018; 71: 19–31
  • Comparison of cell-based assays to quantify treatment effects of anticancer drugs identifies a new application for Bodipy-L-cystine to measure apoptosis SCIENTIFIC REPORTS Kumar, N., Atjei, R., Massoud, T. F., Paulmurugan, R. 2018; 8
  • Comparison of cell-based assays to quantify treatment effects of anticancer drugs identifies a new application for Bodipy-L-cystine to measure apoptosis. Scientific reports Kumar, N., Afjei, R., Massoud, T. F., Paulmurugan, R. 2018; 8 (1): 16363


    Cell-based assays that measure anticancer drug effects are essential for evaluating chemotherapeutic agents. Many assays targeting various cellular mechanisms are available, leading to inconsistent results when using different techniques. We critically compared six common assays, as well as a new assay using Bodipy.FL.L-cystine (BFC), to identify the most accurate and reproducible in measuring anticancer drug effects. We tested three common chemotherapies (methotrexate, paclitaxel, and etoposide) in two cell lines (Ln229 and MDA-MB231). Spectroscopic assays such as Cell Titer Blue, and 2',7'-dichlorofluorescin diacetate (DCFDA) yielded a strong drug dose response, especially for paclitaxel and etoposide (R2=0.9). MTT and Calcein-AM fluorescent dye-based assays were less consistent in that regard. Among three flow cytometry assays, Propidium Iodide (PI)-based DNA content analysis and a new BFC-based glutathione-redox (GSH) assay produced drug dose dependent results. Compared to PI, BFC showed a better correlation (R2=0.7-0.9) in depicting live and apoptotic cells. We found that the combination of Cell Titer Blue spectroscopy and BFC flow cytometry assays were most accurate in assessing anticancer drug effects by clear distinction between live and apoptotic cells, independent of drug mechanism of action. We present a new application of BFC as an agent for measuring cellular apoptosis.

    View details for PubMedID 30397244

  • Tumor Cell-Derived Extracellular Vesicle-Coated Nanocarriers: An Efficient Theranostic Platform for the Cancer-Specific Delivery of Anti-miR-21 and Imaging Agents ACS NANO Bose, R. C., Kumar, S., Zeng, Y., Afjei, R., Robinson, E., Lau, K., Bermudez, A., Habte, F., Pitteri, S. J., Sinclair, R., Willmann, J. K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. 2018; 12 (11): 10817–32
  • Eponymous 'Valves' of the Nasolacrimal Drainage Apparatus: II. Frequency of Visualization on Dacryocystography. Clinical anatomy (New York, N.Y.) Yedavalli, V., Das, D., Massoud, T. F. 2018


    Developmental remnants may follow segmental canalization of ectodermal epithelial cords forming the nasolacrimal drainage apparatus (NDA). This can result in false luminal 'valves' along the path of the NDA, many of which have been named, but most have not been anatomically identified with consistency. By 1908, eight such 'valves' were documented, those of: Foltz, Bochdalek, Rosenmuller, Huschke, Aubaret, Beraud or Krause, Taillefer, and Hasner or Cruveilhier or Bianchi. Digital subtraction dacryocystography (DS-DCG) is the highest spatial resolution imaging technique available to outline in vivo NDA anatomy, luminal profile, and pathology. We believe this is the first report of the conspicuousness and frequency of these 'valves' on DS-DCG. We retrospectively analyzed routine DS-DCGs with normal findings for the presence and frequency of the eight NDA 'valves.' We examined 92 normal DS-DCGs on patients aged 14-82 y (71% female, 29% male). We observed 'valves' most reliably in the inferior nasolacrimal duct: the inferior valve of Hasner (plica lacrimalis) was present in 98.9% of cases, and more superiorly, the valve of Taillefer (93.5%) and the valve of Krause (79.3%). Contrastingly, we infrequently identified the very superior 'valves': Foltz or Bochdalek in 17.1%, Rosenmuller or Huschke in 46.4%, and Auberat in 40% of cases. Therefore, unlike the inferior NDA valves, these more superior 'valves' were less consistently identified and are presumed to be simple mural mucosal irregularities rather than true structural valves. These findings will be useful in diagnostic interpretation of DS-DCGs and therapeutic planning for patients undergoing luminal procedures on the NDA. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30260507

  • Eponymous 'Valves' of the Nasolacrimal Drainage Apparatus: I. A Historical Review. Clinical anatomy (New York, N.Y.) Yedavalli, V., Das, D., Massoud, T. F. 2018


    The nasolacrimal drainage apparatus (NDA) is of interest to anatomists, radiologists, and opthalmologists alike, owing to its intricate luminal contour, complex surrounding structural morphology, and its clinical relevance. Here we review the history of anatomical descriptions of so-called luminal 'valves' of the NDA, including the numerous historical figures whose eponyms adorn the NDA. By 1908, multiple false 'valves' that are likely no more than mounds of mucosa along the NDA had been recorded. In the modern era, these have all been largely considered speculative in nature and function aside from the consistently described true valve of Hasner (plica lacrimalis). Back then, eight so-called 'valves' were believed to be identifiable. These were the 'valves' of Foltz, Bochdalek, Rosenmuller, Huschke, Aubaret, Beraud or Krause, Taillefer, and Hasner or Cruveilhier or Bianchi. With the advent of detailed characterization through modern high-resolution imaging techniques, such as digital subtraction dacryocystography (DS-DCG), many of these valvular folds have come into question owing to their inconsistent identification. This historical review should be useful for greater understanding and accurate contextual interpretation of 'valves' encountered on DS-DCG studies, and in clinical management and therapeutic planning of patients prior to undergoing luminal procedures on the NDA. This article is protected by copyright. All rights reserved.

    View details for PubMedID 30260544

  • The Hemorrhage that Wasn't: Polycythemia Presenting as a Pseudointracranial Hemorrhage in Pedestrian vs Automobile Trauma Alert JOURNAL OF EMERGENCY MEDICINE CASE REPORTS Phillips, A. W., Baird, J. H., Wentland, A. L., Yang, R. L., Massoud, T. F. 2018; 9 (2): 26–29
  • Tumor Cell-Derived Extracellular Vesicle-Coated Nanocarriers: An Efficient Theranostic Platform for the Cancer-Specific Delivery of Anti-miR-21 and Imaging Agents. ACS nano Jc Bose, R. n., Uday Kumar, S. n., Zeng, Y. n., Afjei, R. n., Robinson, E. n., Lau, K. n., Bermudez, A. n., Habte, F. n., Pitteri, S. J., Sinclair, R. n., Willmann, J. K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. n. 2018


    MicroRNAs are critical regulators of cancer initiation, progression, and dissemination. Extensive evidence suggests that the inhibition of over-expressed oncogenic miRNA function can be a robust strategy for anticancer therapy. However, in vivo targeted delivery of miRNA therapeutics to various types of cancers remains a major challenge. Inspired by their natural synthesis and cargo delivery capabilities, researchers have exploited tumor cell-derived extracellular vesicles (TEVs) for the cancer-targeted delivery of therapeutics and theranostics. Here, we investigate a TEV-based nanoplatform for multimodal miRNA delivery and phototherapy treatments as well as the magnetic resonance imaging of cancer. We demonstrated loading of anti-miR-21 that blocks the function of endogenous oncogenic miR-21 over-expressed in cancer cells into and subsequent delivery by TEVs derived from 4T1 cells. We also produced Cy5-anti-miR-21-loaded TEVs from two other cancer cell lines (HepG2 and SKBR3) and confirmed their robust homologous and heterologous transfection efficiency and intracellular Cy5-anti-miR-21 delivery. Additionally, TEV-mediated anti-miR-21 delivery attenuated doxorubicin (DOX) resistance in breast cancer cells with a 3-fold higher cell kill efficiency than in cells treated with DOX alone. We then investigated TEVs as a biomimetic source for the functionalization of gold-iron oxide nanoparticles (GIONs) and demonstrated nanotheranostic properties of TEV-GIONs in vitro. TEV-GIONs demonstrated excellent T2 contrast in in vitro magnetic resonance (MR) imaging and resulted in efficient photothermal effect in 4T1 cells. We also evaluated the biodistribution and theranostic property of anti-miR-21 loaded TEV-GIONs in vivo by labeling with indocyanine green near-infrared dye. We further validated the tumor specific accumulation of TEV-GIONs using MR imaging. Our findings demonstrate that the distribution pattern of the TEV-anti-miR-21-GIONs correlated well with the tumor-targeting capability as well as the activity and efficacy obtained in response to doxorubicin combination treatments. TEVs and TEV-GIONs are promising nanotheranostics for future applications in cancer molecular imaging and therapy.

    View details for PubMedID 30346694

  • TREM1-TARGETED PET IMAGING OF TUMOR-ASSOCIATED MACROPHAGES IN AN ORTHOTOPIC GLIOBLASTOMA MOUSE MODEL Johnson, E., Murty, S., Mayer, A., Tsai, C., Mehta, S., Ilovich, O., Massoud, T., Andreasson, K., James, M. OXFORD UNIV PRESS INC. 2017: 249
  • PKM2 activation sensitizes cancer cells to growth inhibition by 2-deoxy-D-glucose ONCOTARGET Tee, S., Park, J., Hurd, R. E., Brimacombe, K. R., Boxer, M. B., Massoud, T. F., Rutt, B. K., Spielman, D. M. 2017; 8 (53): 90959–68
  • DEVELOPMENT AND EVALUATION OF A NEW HIGHLY SPECIFIC TREM1-SPECIFIC PET TRACER FOR IMAGING MALADAPTIVE INFLAMMATION Johnson, E. M., Mayer, A., Wang, Q., Tsai, C., Mehta, S., Habte, B., Ilovich, O., Massoud, T. F., Andreasson, K. I., James, M. L. WILEY. 2017: 15
  • PKM2 activation sensitizes cancer cells to growth inhibition by 2-deoxy-D-glucose. Oncotarget Tee, S. S., Park, J. M., Hurd, R. E., Brimacombe, K. R., Boxer, M. B., Massoud, T. F., Rutt, B. K., Spielman, D. M. 2017; 8 (53): 90959–68


    Cancer metabolism has emerged as an increasingly attractive target for interfering with tumor growth. Small molecule activators of pyruvate kinase isozyme M2 (PKM2) suppress tumor formation but have an unknown effect on established tumors. We demonstrate that TEPP-46, a PKM2 activator, results in increased glucose consumption, providing the rationale for combining PKM2 activators with the toxic glucose analog, 2-deoxy-D-glucose (2-DG). Combination treatment resulted in reduced viability of a range of cell lines in standard cell culture conditions at concentrations of drugs that had no effect when used alone. This effect was replicated in vivo on established subcutaneous tumors. We further demonstrated the ability to detect acute metabolic differences in combination treatment using hyperpolarized magnetic resonance spectroscopy (MRS). Combination treated tumors displayed a higher pyruvate to lactate 13C-label exchange 2 hr post-treatment. This ability to assess the effect of drugs non-invasively may accelerate the implementation and clinical translation of drugs that target cancer metabolism.

    View details for PubMedID 29207616

  • Engineering Intracellularly Retained Gaussia Luciferase Reporters for Improved Biosensing and Molecular Imaging Applications. ACS chemical biology Gaur, S. n., Bhargava-Shah, A. n., Hori, S. n., Afjei, R. n., Sekar, T. V., Gambhir, S. S., Massoud, T. F., Paulmurugan, R. n. 2017


    Gaussia luciferase (GLUC) is a bioluminescent reporter protein of increasing importance. As a secretory protein, it has increased sensitivity in vitro and in vivo (∼20 000-fold, and ∼1000-fold, respectively) over its competitor, secreted alkaline phosphatase. Unfortunately, this same advantageous secretory nature of GLUC limits its usefulness for many other possible intracellular applications, e.g., imaging signaling pathways in intact cells, in vivo imaging, and in developing molecular imaging biosensors to study protein-protein interactions and protein folding. Hence, to widen the research applications of GLUC, we developed engineered variants that increase its intracellular retention both by modifying the N-terminal secretory signal peptide and by tagging additional sequences to its C-terminal region. We found that when GLUC was expressed in mammalian cells, its N-terminal secretory signal peptide comprising amino acids 1-16 was essential for GLUC folding and functional activity in addition to its inherent secretory property. Modification of the C-terminus of GLUC by tagging a four amino acid (KDEL) endoplasmic reticulum targeting peptide in multiple repeats significantly improved its intracellular retention, with little impact on its folding and enzymatic activity. We used stable cells expressing this engineered GLUC with KDEL repeats to monitor chemically induced endoplasmic reticulum stress on cells. Additionally, we engineered an apoptotic sensor using modified variants of GLUC containing a four amino acid caspase substrate peptide (DEVD) between the GLUC protein and the KDEL repeats. Its use in cell culture resulted in increased GLUC secretion in the growth medium when cells were treated with the chemotherapeutic drugs doxorubicin, paclitaxel, and carboplatin. We thus successfully engineered a new variant GLUC protein that is retained inside cells rather than secreted extracellularly. We validated this novel reporter by incorporating it in biosensors for detection of cellular endoplasmic reticulum stress and caspase activation. This new molecularly engineered enzymatic reporter has the potential for widespread applications in biological research.

    View details for PubMedID 28767220

  • Molecular Imaging Biosensor Monitors p53 Sumoylation in Cells and Living Mice ANALYTICAL CHEMISTRY Sekar, T. V., Foygel, K., Devulapally, R., Kumar, V., Malhotra, S., Massoud, T. F., Paulmurugan, R. 2016; 88 (23): 11420-11428


    Small molecule mediated stabilization of p53 tumor suppressor protein through sumoylation is a promising new strategy for improving cancer chemotherapy. A molecular tool that monitors p53 sumoylation status and expedites screening for drugs that enhance p53 sumoylation would be beneficial. We report a molecularly engineered reporter fragment complementation biosensor based on optical imaging of Firefly luciferase (FLuc), to quantitatively image p53 sumoylation and desumoylation in cells and living mice. We initially characterized this biosensor by successfully imaging sumoylation of several target proteins, achieving significant FLuc complementation for ERα (p < 0.01), p53 (p < 0.005), FKBP12 (p < 0.03), ID (p < 0.03), and HDAC1 (p < 0.002). We then rigorously tested the sensitivity and specificity of the biosensor using several variants of p53 and SUMO1, including deletion mutants, and those with modified sequences containing the SUMO-acceptor site of target proteins. Next we evaluated the performance of the biosensor in HepG2 cells by treatment with ginkgolic acid, a drug that reduces p53 sumoylation, as well as trichostatin A, a potential inducer of p53 sumoylation by enhancement of its nuclear export. Lastly, we demonstrated the in vivo utility of this biosensor in monitoring and quantifying the effects of these drugs on p53 sumoylation in living mice using bioluminescence imaging. Adoption of this biosensor in future high throughput drug screening has the important potential to help identify new and repurposed small molecules that alter p53 sumoylation, and to preclinically evaluate candidate anticancer drugs in living animals.

    View details for DOI 10.1021/acs.analchem.6b02048

    View details for PubMedID 27934110

  • A transgenic mouse model expressing an ER alpha folding biosensor reveals the effects of Bisphenol A on estrogen receptor signaling SCIENTIFIC REPORTS Sekar, T. V., Foygel, K., Massoud, T. F., Gambhir, S. S., Paulmurugan, R. 2016; 6


    Estrogen receptor-α (ERα) plays an important role in normal and abnormal physiology of the human reproductive system by interacting with the endogenous ligand estradiol (E2). However, other ligands, either analogous or dissimilar to E2, also bind to ERα. This may create unintentional activation of ER signaling in reproductive tissues that can lead to cancer development. We developed a transgenic mouse model that constitutively expresses a firefly luciferase (FLuc) split reporter complementation biosensor (NFLuc-ER-LBDG521T-CFLuc) to simultaneously evaluate the dynamics and potency of ligands that bind to ERα. We first validated this model using various ER ligands, including Raloxifene, Diethylstilbestrol, E2, and 4-hydroxytamoxifen, by employing FLuc-based optical bioluminescence imaging of living mice. We then used the model to investigate the carcinogenic property of Bisphenol A (BPA), an environmental estrogen, by long-term exposure at full and half environmental doses. We showed significant carcinogenic effects on female animals while revealing activated downstream ER signaling as measured by bioluminescence imaging. BPA induced tumor-like outgrowths in female transgenic mice, histopathologically confirmed to be neoplastic and epithelial in origin. This transgenic mouse model expressing an ERα folding-biosensor is useful in evaluation of estrogenic ligands and their downstream effects, and in studying environmental estrogen induced carcinogenesis in vivo.

    View details for DOI 10.1038/srep34788

    View details for PubMedID 27721470

  • Glioblastoma Invoking "Killer" Rabbits of the Middle Ages. World neurosurgery Massoud, T. F., Kalnins, A. 2016; 92: 140-141


    We present the unusual appearance on brain magnetic resonance imaging of a glioblastoma with an uncanny shape of a rabbit. By invoking fearsome "killer" rabbits depicted in the art and literature of the Middle Ages, this image is an eerie reminder of the current lethality of this disease. There is a pressing need for more effective treatments for glioblastoma.

    View details for DOI 10.1016/j.wneu.2016.04.116

    View details for PubMedID 27157288

  • Folate Receptor-Targeted Polymeric Micellar Nanocarriers for Delivery of Orlistat as a Repurposed Drug against Triple-Negative Breast Cancer. Molecular cancer therapeutics Paulmurugan, R., Bhethanabotla, R., Mishra, K., Devulapally, R., Foygel, K., Sekar, T. V., Ananta, J. S., Massoud, T. F., Joy, A. 2016; 15 (2): 221-231


    Triple negative breast cancer (TNBC) is a recalcitrant malignancy with no available targeted therapy. Off target effects and poor bioavailability of the FDA approved anti-obesity drug orlistat hinder its clinical translation as a repurposed new drug against TNBC. Here we demonstrate a newly engineered drug formulation for packaging orlistat tailored to TNBC treatment. We synthesized TNBC-specific folate receptor targeted micellar nanoparticles (NPs) carrying orlistat, which improved the solubility (70-80 μg/ml) of this water insoluble drug. The targeted NPs also improved the delivery and bioavailability of orlistat to MDA-MB-231 cells in culture and to tumor xenografts in nude mouse model. We prepared HEA-EHA copolymer micellar NPs by copolymerization of 2-hydroxyethylacrylate (HEA) and 2-ethylhexylacrylate (EHA), and functionalized them with folic acid and an imaging dye. Fluorescence activated cell sorting (FACS) analysis of TNBC cells indicated a dose dependent increase in apoptotic populations in cells treated with free orlistat, orlistat NPs, and folate-receptor targeted Fol-HEA-EHA-orlistat NPs in which Fol-HEA-EHA-orlistat NPs showed significantly higher cytotoxicity than free orlistat. In vitro analysis data demonstrated significant apoptosis at nanomolar concentrations in cells activated through caspase 3 and PARP inhibition. In vivo analysis demonstrated significant antitumor effects in living mice after targeted treatment of tumors, and confirmed by fluorescence imaging. Moreover, Folate receptor targeted Fol-DyLight747-orlistat NPs treated mice exhibited significantly higher reduction in tumor volume compared to control group. Taken together, these results indicate that orlistat packaged in HEA-b-EHA micellar NPs is a highly promising new drug formulation for TNBC therapy.

    View details for DOI 10.1158/1535-7163.MCT-15-0579

    View details for PubMedID 26553061

  • Polymer Nanoparticles Mediated Codelivery of AntimiR-10b and AntimiR-21 for Achieving Triple Negative Breast Cancer Therapy ACS NANO Devulapally, R., Sekar, N. M., Sekar, T. V., Foygel, K., Massoud, T. F., Willmann, J. K., Paulmurugan, R. 2015; 9 (3): 2290-2302


    The current study shows the therapeutic outcome achieved in triple negative breast cancer (TNBC) by simultaneously antagonizing miR-21-induced antiapoptosis and miR-10b-induced metastasis, using antisense-miR-21-PS and antisense-miR-10b-PS delivered by polymer nanoparticles (NPs). We synthesized the antisense-miR-21 and antisense-miR-10b loaded PLGA-b-PEG polymer NPs and evaluated their cellular uptake, serum stability, release profile, and the subsequent synchronous blocking of endogenous miR-21 and miR-10b function in TNBC cells in culture, and tumor xenografts in living animals using molecular imaging. Results show that multitarget antagonization of endogenous miRNAs could be an efficient strategy for targeting metastasis and antiapoptosis in the treatment of metastatic cancer. Targeted delivery of antisense-miR-21 and antisense-miR-10b coloaded urokinase plasminogen activator receptor (uPAR) targeted polymer NPs treated mice showed substantial reduction in tumor growth at very low dose of 0.15 mg/kg, compared to the control NPs treated mice and 40% reduction in tumor growth compared to scramble peptide conjugated NPs treated mice, thus demonstrating a potential new therapeutic option for TNBC.

    View details for DOI 10.1021/nn507465d

    View details for PubMedID 25652012

  • Trends in Performance Indicators of Neuroimaging Anatomy Research Publications: A Bibliometric Study of Major Neuroradiology Journal Output Over Four Decades Based on Web of Science Database CLINICAL ANATOMY Wing, L., Massoud, T. F. 2015; 28 (1): 16-26


    Quantitative, qualitative, and innovative application of bibliometric research performance indicators to anatomy and radiology research and education can enhance cross-fertilization between the two disciplines. We aim to use these indicators to identify long-term trends in dissemination of publications in neuroimaging anatomy (including both productivity and citation rates), which has subjectively waned in prestige during recent years. We examined publications over the last 40 years in two neuroradiological journals, AJNR and Neuroradiology, and selected and categorized all neuroimaging anatomy research articles according to theme and type. We studied trends in their citation activity over time, and mathematically analyzed these trends for 1977, 1987, and 1997 publications. We created a novel metric, "citation half-life at 10 years postpublication" (CHL-10), and used this to examine trends in the skew of citation numbers for anatomy articles each year. We identified 367 anatomy articles amongst a total of 18,110 in these journals: 74.2% were original articles, with study of normal anatomy being the commonest theme (46.7%). We recorded a mean of 18.03 citations for each anatomy article, 35% higher than for general neuroradiology articles. Graphs summarizing the rise (upslope) in citation rates after publication revealed similar trends spanning two decades. CHL-10 trends demonstrated that more recently published anatomy articles were likely to take longer to reach peak citation rate. Bibliometric analysis suggests that anatomical research in neuroradiology is not languishing. This novel analytical approach can be applied to other aspects of neuroimaging research, and within other subspecialties in radiology and anatomy, and also to foster anatomical education. Clin. Anat., 2014. © 2014 Wiley Periodicals, Inc.

    View details for DOI 10.1002/ca.22360

    View details for Web of Science ID 000346273900005

    View details for PubMedID 24431001

  • No Significant Displacement of Basal Brain Structures upon Head Movement: Kinematic MRI Morphometry Relevant to Neuroendoscopy. Journal of neurological surgery. Part A, Central European neurosurgery Horsburgh, A., Kirollos, R. W., Massoud, T. F. 2014; 75 (2): 98-103


    Background An appreciation of normal intracranial anatomy allows optimal planning of trajectories necessary for safe and effective neuroendoscopy. Little information exists on displacement of the caudal brain relative to the skull upon head movement; this could have important implications for planning and performance of neuroendoscopic procedures. We used kinematic magnetic resonance imaging (MRI) studies to examine the morphometric displacement and changing anatomical relationships between the clivus and basal brain structures, intracranial vessels, and subarachnoid spaces.Patients We retrospectively analyzed 15 patients undergoing sagittal T2 kinematic MRI of the head and neck in modest flexion and extension. The angle between a horizontal axial reference plane and a line between the opisthion and the hard palate defined the degree of flexion and extension. We then measured in flexion and extension (1) the cervicomedullary angle (CMA), (2) displacement of the ventral surface of the brainstem (i.e., depth of the prepontine and premedullary cisterns), (3) total sagittal area of the combined suprasellar and ventral brainstem cisterns, and (4) the basilar tip to tuber cinereum distance.Results Relative to neutral head position, a mean extension angle of -15.8 degrees was achieved in all 15 patients, and a mean flexion angle of +9.9 degrees was achieved in 6 patients. The mean CMA was 146 degrees in flexion and 158 degrees in extension. The mean reduction in prepontine and premedullary cistern depth was 0.7 mm and 0.5 mm, respectively, upon flexion from extension. The combined area of suprasellar and ventral brainstem cisterns was minimally reduced from 402 mm2 in flexion to 399 mm2 in extension. The basilar tip did not move significantly from its position in flexion to extension, 5.3 mm to 5.2 mm respectively from the tuber cinereum.Conclusion Kinematic MRI shows minimal brainstem-to-clivus displacement even within minor physiological changes in head flexion. Importantly, these movements are small and there is no significant shift in the position of the basilar tip in modest flexion or extension. These results should be useful for presurgical planning of optimal patient positioning during neuroendoscopic procedures such as third ventriculostomy and the expanded endonasal transsphenoidal approach to the retroclival space.

    View details for DOI 10.1055/s-0033-1342934

    View details for PubMedID 23797619

  • The aqueduct of Sylvius: applied 3-T magnetic resonance imaging anatomy and morphometry with neuroendoscopic relevance. Neurosurgery Matys, T., Horsburgh, A., Kirollos, R. W., Massoud, T. F. 2013; 73 (2): ons132-40


    BACKGROUND:: The aqueduct of Sylvius (AsSylv) is a structure of increasing importance in neuroendoscopic procedures. However, there is currently no clear and adequate description of the normal anatomy of the AqSylv. OBJECTIVE:: To study in detail hitherto unavailable normal MRI morphometry and anatomical variants of the AqSylv. METHODS:: We retrospectively studied normal midsagittal T1-weighted 3T MR images in 100 patients. We measured widths of the AqSylv pars anterior, ampulla, pars posterior, narrowest point, and its length. We recorded angulation of the AqSylv relative to the third ventricle as multiple deviations of the long axis of the AqSylv from Talairach's bicommissural line. We statistically determined age- and gender-related changes in AqSylv morphometry using Pearson's correlation coefficient. We measured angulation of the AqSylv relative to the fourth ventricle and correlated this to the cervico-medullary angle (CMA, a surrogate for head position). RESULTS:: Patients were aged 13- 83 years (55:45, F:M). Mean morphometrics were: width of pars anterior (1.1 mm), ampulla (1.2 mm), pars posterior (1.4 mm), length (14.1 mm), narrowest point (0.9 mm), and angulation in relation to the third (26°) and fourth (18°) ventricles. Age correlated positively with width and negatively with length of the AqSylv. There was no correlation between AqSylv alignment relative to the foramen magnum, and the CMA. CONCLUSION:: Normative dimensions of the AqSylv in vivo are at variance with published cadaveric morphometrics. The AqSylv widens and shortens with cerebral involution. Awareness of these normal morphometrics is highly useful when stent placement is an option during aqueductoplasty. Reported data are valuable in guiding neuroendoscopic management of hydrocephalus and aqueductal stenosis.

    View details for DOI 10.1227/

    View details for PubMedID 23615083

  • The aqueduct of Sylvius: applied 3-T magnetic resonance imaging anatomy and morphometry with neuroendoscopic relevance. Neurosurgery Matys, T., Horsburgh, A., Kirollos, R. W., Massoud, T. F. 2013; 73 (2): 132-140

    View details for DOI 10.1227/

    View details for PubMedID 23615083

  • Tuber cinereum proximity to critical major arteries: a morphometric imaging analysis relevant to endoscopic third ventriculostomy ACTA NEUROCHIRURGICA Horsburgh, A., Matys, T., Kirollos, R. W., Massoud, T. F. 2013; 155 (5): 891-900


    Arterial bleeding in the interpeduncular fossa is a dreaded complication of endoscopic third ventriculostomy (ETV). When the "safe zone" of the tuber cinereum (TC) is fenestrated, the basilar artery tip (BT) or its branches may be encountered below the third ventriclular floor. Major arterial injuries might be avoided by careful preoperative planning. We aimed to establish previously unavailable normal magnetic resonance imaging (MRI) and MR angiographic (MRA) morphometry and configuration of the BT and posterior cerebral artery P1 segments relative to the TC.We analyzed images of 82 patients with non-dilated ventricles (mean Evans' index 0.26), and lying in a neutral head position (mean cervico-medullary angle 141°). We cross-referenced axial MRAs with sagittal MRIs to measure distances of BT and P1 segments from the TC, and to classify the location of the BT in the interpeduncular and suprasellar cisterns. We correlated the sagittal areas of these cisterns and patients' ages with the TC-to-artery distances using regression analysis.The BT, right P1 and left P1 segments were a mean 4.9 mm, 5.5 mm, and 5.7 mm respectively from the TC. Seventy-four percent of BTs were anterior to the mammillary bodies. These distances and locations did not correlate with age (mean 53 years) or size of basal cisterns.The normal BT and P1 segments are anatomically close to the TC and potentially at risk during ETV in adults of all ages. The new morphometric data presented, along with cross-referencing of preoperative multiplanar images, could help reduce vascular complications during ETV.

    View details for DOI 10.1007/s00701-013-1661-9

    View details for Web of Science ID 000317679800021

    View details for PubMedID 23468037

  • Normative dimensions and symmetry of the lacrimal drainage system on dacryocystography: statistical analysis of morphometric characteristics FOLIA MORPHOLOGICA Horsburgh, A., Massoud, T. F. 2013; 72 (2): 137-141


    Asymmetric lacrimal flow occurs in females more than males. We hypothesised that the normal lacrimal drainage system (LDS) may show subtle left-rightasymmetry in morphometry when imaged on dacryocystography (DCG).We retrospectively reviewed 60 normal bilateral LDSs.Images were analysed for 7 parameters: (1) combined length of either the superioror inferior canaliculus plus common canaliculus, (2) angle of insertion of common canaliculus into lacrimal sac (LS), (3, 4) length and width of the LS, (5) length of thenasolacrimal duct (NLD), and (6, 7) width of proximal and distal NLD. We testedthe effect of independent variables (age, gender, and side) on each dependentvariable (length, width, or angle) using regression analysis. We used a Studentt-test for independent samples to statistically compare bilateral LDSs.Patient median age was 62 years, and male:female ratio was 27:73. Mean dimensions and angles for all LDSs were: (1) 14.5 mm, (2) 57°,(3) 11.6 mm, (4) 2.1 mm, (5) 20.7 mm, (6) 1.4 mm, and (7) 1.8 mm. No independent variable affected variation in length, width, or angle. No significant difference emerged between dimensions of right and left LDSs in both sexes.Conclusions: A degree of affective lateralisation in the brain is known to result inlacrimal flow asymmetry after mood manipulation. We show that this is not reflected in LDS anatomy. Moreover, our detailed morphometric data can aid in therapeuticplanning of LDS luminal procedures, especially when DCG images of one LDS are used as a road map for contralateral interventions.

    View details for DOI 10.5603/FM.2013.0023

    View details for Web of Science ID 000320777400009

    View details for PubMedID 23740501

  • The circumventricular organs of the brain: conspicuity on clinical 3T MRI and a review of functional anatomy SURGICAL AND RADIOLOGIC ANATOMY Horsburgh, A., Massoud, T. F. 2013; 35 (4): 343-349


    The circumventricular organs (CVOs) occupy seven midline locations around the ventricles. They contain specialized ependymal cells called tanycytes and have an incomplete blood-brain barrier (BBB). We hypothesized that appearances of the lesser known CVOs on contrast-enhanced MRI might lead to confusion in image interpretation whereby they might be mistaken for pathology-related abnormal contrast enhancement. We therefore assessed the normal appearances and prevalence of contrast enhancement of the CVOs on routine clinical brain MRI and reviewed the functional anatomy of the CVOs.We retrospectively reviewed sagittal and coronal pre- and post-contrast T1-weighted brain 3T MR images in 100 adult patients with normal findings. We assessed the presence of the median eminence (ME), neurohypophysis (NH), pineal gland (PG), subforniceal organ (SFO), organum vasculosum of the lamina terminalis (OVLT), subcommissural organ (SCO), and the area postrema (AP).The frequency of contrast enhancement of the seven CVOs was as follows: ME in 100 %, NH in 96 %, PG in 84 %, SFO in 1 %, OVLT in 34 %, SCO in 0 %, and AP in 2 %.The main CVOs (ME, NH, and PG) are well known and appreciated on brain imaging. However, there is a little awareness of the minor CVOs among neuroimagers. This is the first study of contrast enhancement prevalence of the SF, OV, SC, and AP on brain MRI. All the latter are small, faint, rarely visualized, and therefore not likely to cause misinterpretation with significant sources of pathology that cause breakdown of the BBB, such as tumor or inflammation.

    View details for DOI 10.1007/s00276-012-1048-2

    View details for Web of Science ID 000317978800010

    View details for PubMedID 23247732

  • Lessons Learned From Unintended Sublingual Sialography: Imaging Anatomy, Technical Considerations, and Diagnostic Implications AMERICAN JOURNAL OF ROENTGENOLOGY Horsburgh, A., Massoud, T. F. 2013; 200 (4): 879-883


    Digital subtraction sialography of the sublingual glands has not been reported previously, to our knowledge. We present a case series in which unintended digital subtraction sialography of the sublingual glands occurred during attempts at submandibular digital subtraction sialography. In four of the six cases, a mistaken diagnosis of severe sublingual gland sialectasis was made.Because of the unique histologic characteristics of the sublingual glands, knowledge of the technical aspects of sublingual duct cannulation and the relevant imaging anatomy is necessary to avoid image misinterpretation and clinical mismanagement.

    View details for DOI 10.2214/AJR.12.8841

    View details for Web of Science ID 000316622100042

    View details for PubMedID 23521464

  • Is higher choroid plexus 'load' an aetiologic factor in idiopathic intracranial hypertension? A clinico-imaging morphometric correlative study CEPHALALGIA Horsburgh, A., Massoud, T. F. 2013; 33 (1): 20-24


    Idiopathic intracranial hypertension (IIH) is a condition of raised cerebrospinal fluid (CSF) pressure with normal ventricular size. Although the pathogenesis of IIH remains controversial, increased CSF formation may be important. We hypothesised that if increased CSF formation was an aetiologic factor, it might result in a macroscopic increase in size of the choroid plexus (CP).We retrospectively studied 50 patients with IIH. Total size of the CP was estimated on computed tomography (CT) venograms from the sum of axial areas measured at three locations. Results were compared with the CP load of 50 matched controls on post-contrast head CTs. Evans Index was measured to exclude ventriculomegaly. Results were analysed using a Student's t test for independent samples (p < 0.05), and the effect of ICP was tested on the dependent variable (area of CP) using regression analysis.There was no significant difference in the size of the CP glomus, total axial areas of the CP between IIH patients (183 mm(2)) and controls (178 mm(2)) and no correlation between the 'load' of CP and the degree of intracranial pressure (ICP) (R (2)< 0.02).If increased CSF formation is an aetiologic factor in IIH, this is not reflected in a corresponding raised 'load' of CP.

    View details for DOI 10.1177/0333102412465202

    View details for Web of Science ID 000312305800002

    View details for PubMedID 23136206

  • A c-Myc Activation Sensor-Based High-Throughput Drug Screening Identifies an Antineoplastic Effect of Nitazoxanide Mol Cancer Ther Fan-Minogue, H., Bodapati , S., Solow-Cordero, D., Fan, A., Paulmurugan, R., et al 2013
  • Primary Cerebral Lymphoma Causing Remitting and Relapsing Neurological Symptoms Journal of Medical Cases Stoker, T., Young, A., Massoud, T. F., Patani, R., Manford, M. 2013; 4 (6): 420-423
  • The role of salivary duct morphology in the aetiology of sialadenitis: statistical analysis of sialographic features INTERNATIONAL JOURNAL OF ORAL AND MAXILLOFACIAL SURGERY Horsburgh, A., Massoud, T. F. 2013; 42 (1): 124-128


    Morphologic characteristics of salivary ducts may contribute to stagnation of saliva. The authors hypothesized that some features might contribute to development of submandibular and parotid sialadenitis. 106 digital subtraction sialograms (DSS) were retrospectively reviewed for: degree of sialadenitis, length of Wharton's and Stensen's ducts (SD), and angle of Wharton's duct (WD) genu. Student's t test was used for independent samples to statistically compare normal and sialadenitis groups. The effect of independent variables (age, gender, side, degree of sialadenitis) on the dependent variable (length or angle) were tested using regression analysis. Submandibular duct sialadenitis was mild (67%), moderate (8%), or severe (25%); parotid duct sialadenitis was mild (57%), moderate (18%), or severe (25%). Mean length of normal WD was 58.2 mm, and 56.3 mm with sialadenitis. Mean length of normal SD was 52 mm, and 53 mm with sialadenitis. The mean angle of WD genu was 115° in normal ducts, and 119° with sialadenitis. None of the independent variables affected variation in length or angle. There were no statistical differences in duct length or measured angle between normal and sialadenitis groups. There is a wide variation in salivary duct morphology but this does not appear to be associated with the cause of sialadenitis.

    View details for DOI 10.1016/j.ijom.2012.10.006

    View details for Web of Science ID 000315013500021

    View details for PubMedID 23137733

  • Bochdalek's flower basket: applied neuroimaging morphometry and variants of choroid plexus in the cerebellopontine angles NEURORADIOLOGY Horsburgh, A., Kirollos, R. W., Massoud, T. F. 2012; 54 (12): 1341-1346


    Protrusions of fourth ventricular choroid plexus through the foramina of Luschka are called 'Bochdalek's flower basket' (BochFB). The bulbous terminal expansions (cornucopiae) extend into the cerebellopontine angle (CPA) cisterns. We studied and reviewed the normal imaging anatomy, morphometry and anatomical variants of BochFB.We retrospectively analysed normal brain imaging findings on axial pre- and post-contrast CT scans and enhanced axial T1-weighted MRIs of 200 patients. We assessed BochFB for: (a) calcification, (b) lateral extension, (c) enhancement pattern, (d) cornucopiae shape, (e) symmetry and (f) proximity to tortuous vertebral arteries and morphometry of cornucopiae size and length of BochFB limbs.BochFB calcification was found in 38 % of patients aged over 51 years. Lateral extension of BochFB into the CPA cistern was prominent in 75 % on CT and 96 % on MRI. The mean length of these extensions was 23.6 mm. BochFB enhanced strongly in 47 % on CT and 66 % on MRI. The BochFB cornucopiae were bulbous in 51 % on CT and 54 % on MRI. The mean width of bulbous cornucopiae was 3.5 mm. Bilateral BochFB symmetry was found in 71 % on CT and 80 % on MRI. Six to 8 % of tortuous left vertebral arteries were close to BochFB.The cornucopiae are particularly well demonstrated on post-contrast MRI. However several sources of error in image interpretation may arise when imaging the normal BochFB on routine head CT and MRI. Difficulties in analysis arise especially on CT because of physiologic calcification, asymmetry, and the bulbous cornucopiae being mistaken for aneurysms.

    View details for DOI 10.1007/s00234-012-1065-1

    View details for Web of Science ID 000312336700006

    View details for PubMedID 22777194

  • Discovery and validation of small-molecule heat-shock protein 90 inhibitors through multimodality molecular imaging in living subjects PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Chan, C. T., Reeves, R. E., Geller, R., Yaghoubi, S. S., Hoehne, A., Solow-Cordero, D. E., Chiosis, G., Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2012; 109 (37): E2476-E2485


    Up-regulation of the folding machinery of the heat-shock protein 90 (Hsp90) chaperone protein is crucial for cancer progression. The two Hsp90 isoforms (α and β) play different roles in response to chemotherapy. To identify isoform-selective inhibitors of Hsp90(α/β)/cochaperone p23 interactions, we developed a dual-luciferase (Renilla and Firefly) reporter system for high-throughput screening (HTS) and monitoring the efficacy of Hsp90 inhibitors in cell culture and live mice. HTS of a 30,176 small-molecule chemical library in cell culture identified a compound, N-(5-methylisoxazol-3-yl)-2-[4-(thiophen-2-yl)-6-(trifluoromethyl)pyrimidin-2-ylthio]acetamide (CP9), that binds to Hsp90(α/β) and displays characteristics of Hsp90 inhibitors, i.e., degradation of Hsp90 client proteins and inhibition of cell proliferation, glucose metabolism, and thymidine kinase activity, in multiple cancer cell lines. The efficacy of CP9 in disrupting Hsp90(α/β)/p23 interactions and cell proliferation in tumor xenografts was evaluated by non-invasive, repetitive Renilla luciferase and Firefly luciferase imaging, respectively. At 38 h posttreatment (80 mg/kg × 3, i.p.), CP9 led to selective disruption of Hsp90α/p23 as compared with Hsp90β/p23 interactions. Small-animal PET/CT in the same cohort of mice showed that CP9 treatment (43 h) led to a 40% decrease in (18)F-fluorodeoxyglucose uptake in tumors relative to carrier control-treated mice. However, CP9 did not lead to significant degradation of Hsp90 client proteins in tumors. We performed a structural activity relationship study with 62 analogs of CP9 and identified A17 as the lead compound that outperformed CP9 in inhibiting Hsp90(α/β)/p23 interactions in cell culture. Our efforts demonstrated the power of coupling of HTS with multimodality molecular imaging and led to identification of Hsp90 inhibitors.

    View details for DOI 10.1073/pnas.1205459109

    View details for PubMedID 22895790

  • In Vitro and in Vivo Molecular Imaging of Estrogen Receptor alpha and beta Homo- and Heterodimerization: Exploration of New Modes of Receptor Regulation MOLECULAR ENDOCRINOLOGY Paulmurugan, R., Tamrazi, A., Massoud, T. F., Katzenellenbogen, J. A., Gambhir, S. S. 2011; 25 (12): 2029-2040


    Estrogen receptor (ER) biology reflects the actions of estrogens through the two receptors, ERα and ERβ, although little is known regarding the preference for formation of ER homo- vs. heterodimers, and how this is affected by the level of ligand occupancy and preferential ligand affinity for one of the ER subtypes. In this report, we use a split optical reporter-protein complementation system to demonstrate the physical interaction between ERα and ERβ in response to different ER ligands in cells and, for the first time, by in vivo imaging in living animals. The genetically encoded reporter vectors constructed with the ligand-binding domains of ERα and ERβ, fused to split firefly or Renilla luciferase (Fluc or hRluc) fragments, were used for this study. This molecular proteomic technique was used to detect ERα/ERα or ERβ/ERβ homodimerization, or ERα/ERβ heterodimerization induced by ER subtype-selective and nonselective ligands, and selective ER modulators (SERM), as well as in dimers in which one mutant monomer was unable to bind estradiol. The SERM-bound ERα and ERβ form the strongest dimers, and subtype-preferential homodimerization was seen with ERα-selective ligands (methyl piperidino pyrazole/propyl pyrazole triol) and the ERβ-selective ligands (diarylpropionitrile/tetrahydrochrysene/genistein). We also demonstrated that a single ligand-bound monomer can form homo- or heterodimers with an apo-monomer. Xenografts of human embryonic kidney 293T cells imaged in living mice by bioluminescence showed real-time ligand induction of ERα/ERβ heterodimerization and reversal of dimerization upon ligand withdrawal. The results from this study demonstrate the value of the split luciferase-based complementation system for studying ER-subtype interactions in cells and for evaluating them in living animals by noninvasive imaging. They also probe what combinations of ERα and ERβ dimers might be the mediators of the effects of different types of ER ligands given at different doses.

    View details for DOI 10.1210/me.2011-1145

    View details for PubMedID 22052998

  • Gold Nanoparticles: A Revival in Precious Metal Administration to Patients NANO LETTERS Thakor, A. S., Jokerst, J., Zavaleta, C., Massoud, T. F., Gambhir, S. S. 2011; 11 (10): 4029-4036


    Gold has been used as a therapeutic agent to treat a wide variety of rheumatic diseases including psoriatic arthritis, juvenile arthritis, and discoid lupus erythematosus. Although the use of gold has been largely superseded by newer drugs, gold nanoparticles are being used effectively in laboratory based clinical diagnostic methods while concurrently showing great promise in vivo either as a diagnostic imaging agent or a therapeutic agent. For these reasons, gold nanoparticles are therefore well placed to enter mainstream clinical practice in the near future. Hence, the present review summarizes the chemistry, pharmacokinetics, biodistribution, metabolism, and toxicity of bulk gold in humans based on decades of clinical observation and experiments in which gold was used to treat patients with rheumatoid arthritis. The beneficial attributes of gold nanoparticles, such as their ease of synthesis, functionalization, and shape control are also highlighted demonstrating why gold nanoparticles are an attractive target for further development and optimization. The importance of controlling the size and shape of gold nanoparticles to minimize any potential toxic side effects is also discussed.

    View details for DOI 10.1021/nl202559p

    View details for PubMedID 21846107

  • Bioluminescence resonance energy transfer (BRET) imaging of protein-protein interactions within deep tissues of living subjects PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Dragulescu-Andrasi, A., Chan, C. T., De, A., Massoud, T. F., Gambhir, S. S. 2011; 108 (29): 12060-12065


    Identifying protein-protein interactions (PPIs) is essential for understanding various disease mechanisms and developing new therapeutic approaches. Current methods for assaying cellular intermolecular interactions are mainly used for cells in culture and have limited use for the noninvasive assessment of small animal disease models. Here, we describe red light-emitting reporter systems based on bioluminescence resonance energy transfer (BRET) that allow for assaying PPIs both in cell culture and deep tissues of small animals. These BRET systems consist of the recently developed Renilla reniformis luciferase (RLuc) variants RLuc8 and RLuc8.6, used as BRET donors, combined with two red fluorescent proteins, TagRFP and TurboFP635, as BRET acceptors. In addition to the native coelenterazine luciferase substrate, we used the synthetic derivative coelenterazine-v, which further red-shifts the emission maxima of Renilla luciferases by 35 nm. We show the use of these BRET systems for ratiometric imaging of both cells in culture and deep-tissue small animal tumor models and validate their applicability for studying PPIs in mice in the context of rapamycin-induced FK506 binding protein 12 (FKBP12)-FKBP12 rapamycin binding domain (FRB) association. These red light-emitting BRET systems have great potential for investigating PPIs in the context of drug screening and target validation applications.

    View details for DOI 10.1073/pnas.1100923108

    View details for PubMedID 21730157

  • The Fate and Toxicity of Raman-Active Silica-Gold Nanoparticles in Mice SCIENCE TRANSLATIONAL MEDICINE Thakor, A. S., Luong, R., Paulmurugan, R., Lin, F. I., Kempen, P., Zavaleta, C., Chu, P., Massoud, T. F., Sinclair, R., Gambhir, S. S. 2011; 3 (79)


    Raman spectroscopy is an optical imaging method that is based on the Raman effect, the inelastic scattering of a photon when energy is absorbed from light by a surface. Although Raman spectroscopy is widely used for chemical and molecular analysis, its clinical application has been hindered by the inherently weak nature of the Raman effect. Raman-silica-gold-nanoparticles (R-Si-Au-NPs) overcome this limitation by producing larger Raman signals through surface-enhanced Raman scattering. Because we are developing these particles for use as targeted molecular imaging agents, we examined the acute toxicity and biodistribution of core polyethylene glycol (PEG)-ylated R-Si-Au-NPs after different routes of administration in mice. After intravenous administration, PEG-R-Si-Au-NPs were removed from the circulation by macrophages in the liver and spleen (that is, the reticuloendothelial system). At 24 hours, PEG-R-Si-Au-NPs elicited a mild inflammatory response and an increase in oxidative stress in the liver, which subsided by 2 weeks after administration. No evidence of significant toxicity was observed by measuring clinical, histological, biochemical, or cardiovascular parameters for 2 weeks. Because we are designing targeted PEG-R-Si-Au-NPs (for example, PEG-R-Si-Au-NPs labeled with an affibody that binds specifically to the epidermal growth factor receptor) to detect colorectal cancer after administration into the bowel lumen, we tested the toxicity of the core nanoparticle after administration per rectum. We observed no significant bowel or systemic toxicity, and no PEG-R-Si-Au-NPs were detected systemically. Although additional studies are required to investigate the long-term effects of PEG-R-Si-Au-NPs and their toxicity when carrying the targeting moiety, the results presented here support the idea that PEG-R-Si-Au-NPs can be safely used in living subjects, especially when administered rectally.

    View details for DOI 10.1126/scitranslmed.3001963

    View details for PubMedID 21508310

  • Oxidative Stress Mediates the Effects of Raman-Active Gold Nanoparticles in Human Cells SMALL Thakor, A. S., Paulmurugan, R., Kempen, P., Zavaleta, C., Sinclair, R., Massoud, T. F., Gambhir, S. S. 2011; 7 (1): 126-136


    Polyethylene glycol (PEG)ylated Raman-active gold nanoparticles (PEG-R-AuNPs) consist of an interchangeable Raman organic molecule layer held onto a gold nanocore by a silica shell. PEG-R-AuNPs have been shown preclinically to increase the sensitivity and specificity of Raman spectroscopy, with picomolar sensitivity and multiplexing capabilities. Although clinical trials are being designed to use functionalized PEG-R-AuNPs in various applications (e.g., to target dysplastic bowel lesions during colonoscopy), the effects of these nanoparticles on human cells remain unknown. The occurrence and mechanisms underlying any potential cytotoxicity induced by these nanoparticles (0-1000 PEG-R-AuNPs/cell) are investigated in immortalized human HeLa and HepG2 cell lines at several time points (0-48 h) after exposure. Using fluorometric assays, cell viability (MTT), reactive oxygen species (ROS) generation (dichlorofluorescein diacetate), protein oxidation (protein carbonyl content), and total cellular antioxidant concentrations the concentrations (metmyoblobin-induced oxidation of ABTS) are assessed. Analysis of lipid oxidation using an enzyme immunoassay (8-isoprostane concentrations), gene expression of antioxidant enzymes using quantitative reverse transcription polymerase chain reactions, and the intracellular location of PEG-R-AuNPs using transmission electron microscopy is also undertaken. PEG-R-AuNPs cause no cytotoxicity in either HeLa or HepG2 cells in the acute setting as ROS generation is balanced by antioxidant enzyme upregulation. Following prolonged exposures (48 h) at relatively high concentrations (1000 PEG-R-AuNPs/cell), nanoparticles are found within vesicles inside cells. Under these conditions, a minimal amount of cytotoxicity is seen in both cell lines owing to increases in cellular oxidative stress, most likely due to ROS overwhelming the antioxidant defenses. Evidence of oxidative stress-induced damage includes increased lipid and protein oxidation. Although further in vivo toxicity studies are necessary, these initial encouraging results show that PEG-R-AuNPs cause minimal toxicity in human cells in the acute setting, which bodes well for potential future applications of these nanoparticles in living subjects.

    View details for DOI 10.1002/smll.201001466

    View details for PubMedID 21104804

  • Noninvasive molecular imaging of c-Myc activation in living mice PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Fan-Minogue, H., Cao, Z., Paulmurugan, R., Chan, C. T., Massoud, T. F., Felsher, D. W., Gambhir, S. S. 2010; 107 (36): 15892-15897


    The cytoplasmic Myc protein (c-Myc) regulates various human genes and is dysregulated in many human cancers. Phosphorylation mediates the protein activation of c-Myc and is essential for the function of this transcription factor in normal cell behavior and tumor growth. To date, however, the targeting of Myc as a therapeutic approach for cancer treatment has been achieved primarily at the nonprotein level. We have developed a molecular imaging sensor for noninvasive imaging of c-Myc activity in living subjects using a split Firefly luciferase (FL) complementation strategy to detect and quantify the phosphorylation-mediated interaction between glycogen synthase kinase 3beta (GSK3beta) and c-Myc. This sensor system consists of two fusion proteins, GSK 35-433-CFL and NFL-c-Myc, in which specific fragments of GSK3beta and c-Myc are fused with C-terminal and N-terminal fragments of the split FL, respectively. The sensor detects phosphorylation-specific GSK3beta-c-Myc interaction, the imaging signal of which correlates with the steady-state and temporal regulation of c-Myc phosphorylation in cell culture. The sensor also detects inhibition of c-Myc activity via differential pathways, allowing noninvasive monitoring of c-Myc-targeted drug efficacy in intact cells and living mice. Notably, this drug inhibition is detected before changes in tumor size are apparent in mouse xenograft and liver tumor models. This reporter system not only provides an innovative way to investigate the role of functional c-Myc in normal and cancer-related biological processes, but also facilitates c-Myc-targeted drug development by providing a rapid quantitative approach to assessing cancer response to therapy in living subjects.

    View details for DOI 10.1073/pnas.1007443107

    View details for PubMedID 20713710

  • A Novel Estrogen Receptor Intramolecular Folding-based Titratable Transgene Expression System MOLECULAR THERAPY Paulmurugan, R., Padmanabhan, P., Ahn, B., Ray, S., Willmann, J. K., Massoud, T. F., Biswal, S., Gambhir, S. S. 2009; 17 (10): 1703-1711


    The use of regulated gene expression systems is important for successful gene therapy applications. In this study, ligand-induced structural change in the estrogen receptor (ER) was used to develop a novel ER intramolecular folding-based transcriptional activation system. The system was studied using ER-variants of different lengths, flanked on either side by the GAL4-DNA-binding domain and the VP16-transactivation domain (GAL4(DBD)-ER-VP16). The ER ligands of different types showed efficient ligand-regulated transactivation. We also characterized a bidirectional transactivation system based on the ER and demonstrated its utility in titrating both reporter and therapeutic gene expression. The ligand-regulated transactivation system developed by using a mutant form of the ER (G521T, lacking affinity for the endogenous ligand 17beta-estradiol, whereas maintaining affinity for other ligands) showed efficient activation by the ligand raloxifene in living mice without significant interference from the circulating endogenous ligand. The ligand-regulated transactivation system was used to test the therapeutic efficiency of the tumor suppressor protein p53 in HepG2 (p53(+/+)) and SKBr3 (p53(-/-)/mutant-p53(+/+)) cells in culture and tumor xenografts in living mice. The multifunctional capabilities of this system should be useful for gene therapy applications, to study ER biology, to evaluate gene regulation, ER ligand screening, and ER ligand biocharacterization in cells and living animals.

    View details for DOI 10.1038/mt.2009.171

    View details for PubMedID 19654568

  • Double superior vena cavae. BMJ case reports Thakor, A. S., Massoud, T. 2009; 2009

    View details for DOI 10.1136/bcr.10.2008.1098

    View details for PubMedID 21686460

  • Molecular imaging of reporter gene expression in prostate cancer: An overview 12th Meeting of the International-Scientific-Committee-of-Radionuclides-in-Nephrourology Singh, A., Massoud, T. F., Deroose, C., Gambhir, S. S. W B SAUNDERS CO-ELSEVIER INC. 2008: 9–19


    Prostate cancer remains an important and growing health problem. Advances in imaging of prostate cancer may help to achieve earlier and more accurate diagnosis and treatment. We review the various strategies using reporter genes for molecular imaging of prostate cancer. These approaches are emerging as valuable tools for monitoring gene expression in laboratory animals and humans. Further development of more sensitive and selective reporters, combined with improvements in detection technology, will consolidate the position of reporter gene imaging as a versatile method for understanding of intracellular biological processes and the underlying molecular basis of prostate cancer, as well as potentially establishing a future role in the clinical management of patients afflicted with this disease.

    View details for DOI 10.1053/j.semnuclmed.2007.09.002

    View details for Web of Science ID 000252068300003

    View details for PubMedID 18096460

  • Molecular imaging of homodimeric protein-protein interactions in living subjects FASEB JOURNAL Massoud, T. F., Paulmurugan, R., Gambhir, S. S. 2004; 18 (7): 1105-?
  • Molecular imaging of drug-modulated protein-protein interactions in living subjects CANCER RESEARCH Paulmurugan, R., Massoud, T. F., Huang, J., Gambhir, S. S. 2004; 64 (6): 2113-2119


    Networks of protein interactions mediate cellular responses to environmental stimuli and direct the execution of many different cellular functional pathways. Small molecules synthesized within cells or recruited from the external environment mediate many protein interactions. The study of small molecule-mediated interactions of proteins is important to understand abnormal signal transduction pathways in cancer and in drug development and validation. In this study, we used split synthetic renilla luciferase (hRLUC) protein fragment-assisted complementation to evaluate heterodimerization of the human proteins FRB and FKBP12 mediated by the small molecule rapamycin. The concentration of rapamycin required for efficient dimerization and that of its competitive binder ascomycin required for dimerization inhibition were studied in cell lines. The system was dually modulated in cell culture at the transcription level, by controlling nuclear factor kappaB promoter/enhancer elements using tumor necrosis factor alpha, and at the interaction level, by controlling the concentration of the dimerizer rapamycin. The rapamycin-mediated dimerization of FRB and FKBP12 also was studied in living mice by locating, quantifying, and timing the hRLUC complementation-based bioluminescence imaging signal using a cooled charged coupled device camera. This split reporter system can be used to efficiently screen small molecule drugs that modulate protein-protein interactions and also to assess drugs in living animals. Both are essential steps in the preclinical evaluation of candidate pharmaceutical agents targeting protein-protein interactions, including signaling pathways in cancer cells.

    View details for PubMedID 15026351

  • Recent progress in medical imaging: Molecular imaging in living subjects Journal of the Korean Society of Medical Informatics Min JJ, Massoud TF 2003; 9: 349-373
  • Experimental arteriovenous malformations modeling in laboratory sheep versus swine AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F. 2000; 21 (5): 985-988

    View details for Web of Science ID 000086983400040

    View details for PubMedID 10815687

  • Transvenous Doppler guidewire sonographic monitoring during treatment of a complex vertebral arteriovenous fistula associated with neurofibromatosis Type 1 NEURORADIOLOGY Murayama, Y., Usami, S., Abe, T., Hata, Y., Ganaha, F., Massoud, T. F. 1999; 41 (5): 328-333


    A Doppler sonographic guidewire was used to monitor incremental changes in draining vein (DV) flow during endovascular occlusion of a complex vertebral arteriovenous fistula (AVF) in a patient with neurofibromatosis type 1. Transvenous monitoring of average peak velocity (APV) and the maximum-minus-minimum peak velocity (MxPV-MnPV) demonstrated a progression from a highly pulsatile, fast flow before embolization to a nonpulsatile, slow flow indicating a successful occlusion of the AVF (hemodynamic endpoint of treatment). Prior to this, apparent angiographic occlusion of the AVF was thought to signify a successful endpoint; however, persistently elevated values for APV and MxPV-MnPV in the DV signalled the presence of an additional contralateral arterial contribution. Transvenous monitoring of flow velocity appears to be ideally suited to establishing a hemodynamic endpoint of embolotherapy in the presence of complex arteriovenous shunting, as may occur with the vasculopathy of neurofibromatosis.

    View details for Web of Science ID 000080530600004

    View details for PubMedID 10379588

  • Anatomical and morphological factors correlating with rupture of intracranial aneurysms in patients referred for endovascular treatment NEURORADIOLOGY Hademenos, G. J., Massoud, T. F., Turjman, F., Sayre, J. W. 1998; 40 (11): 755-760


    The size of intracranial aneurysms is the only characteristic shown to correlate with their rupture. However, the critical size for rupture has varied considerably among previous accounts and remains a point of controversy. Our goal was to identify statistically significant clinical and morphological factors predictive of the occurrence of rupture and aneurysm size in patients referred for endovascular treatment. We retrospectively recorded the following factors from 74 patients who presented with ruptured (40) or unruptured (34) aneurysms: aneurysm morphology (uni/multilobulated), location (anterior/posterior), maximum diameter, diameter of the neck, and the patient's age and sex. We performed stepwise discriminant, and stepwise and logistic regression analysis to identify factors predicting rupture and the size of the aneurysm at rupture. The mean diameter of the ruptured aneurysms was 11.9+/-6.3 mm, range 3.0-33.0 mm, and that of the unruptured aneurysm 13.5+/-5.8 mm, range 5.0-30 mm. Stepwise discriminant analysis identified aneurysm morphology (P < 0.001) and location in the intracranial circulation (P < 0.001) as statistically significant factors in predicting rupture. Stepwise regression analysis revealed that aneurysm morphology and the size of the neck were predictors of aneurysm size at rupture.

    View details for Web of Science ID 000077198300013

    View details for PubMedID 9860129

  • Theoretical modelling of arteriovenous malformation rupture risk: a feasibility and validation study MEDICAL ENGINEERING & PHYSICS Gao, E. Z., Young, W. L., Hademenos, G. J., Massoud, T. F., Sciacca, R. R., Ma, Q. Y., Joshi, S., Mast, H., Vulliemoz, S., Pile-Spellman, J. 1998; 20 (7): 489-501


    To explore the feasibility of using a theoretical computational model to simulate the risk of spontaneous arteriovenous malformation (AVM) haemorrhage.Data from 12 patients were collected from a prospective databank which documented the angioarchitecture and morphological characteristics of the AVM and the feeding mean arterial pressure (FMAP) measured during initial superselective angiography prior to any treatment. Using the data, a computational model of the cerebral circulation and the AVM was constructed for each patient (patient-specific model). Two model risk (Risk(model)) calculations (haemodynamic- and structural-weighted estimates) were performed by using the patient-specific models. In our previously developed method of haemodynamic-weighted estimate, Risk(model) was calculated with the simulated intranidal pressures related to its maximal and minimal values. In the method of structural-weighted estimate developed and described in this paper, the vessel mechanical properties and probability calculation were considered in more detail than in the haemodynamic-weighted estimate. Risk(model) was then compared to experimentally determined risk which was calculated using a statistical method for determining the relative risk of having initially presented with AVM haemorrhage, termed Risk(exp).The Risk(model) calculated by both haemodynamic- and structural-weighted estimates correlated with experimental risks with chi2 = 6.0 and 0.64, respectively. The risks of the structural-weighted estimate were more correlated to experimental risks.Using two different approaches to the calculation of AVM haemorrhage risk, we found a general agreement with independent statistical estimates of haemorrhagic risk based on patient data. Computational approaches are feasible; future work can focus on specific pathomechanistic questions. Detailed patient-specific computational models can also be developed as an adjunct to individual patient risk assessment for risk-stratification purposes.

    View details for Web of Science ID 000076844900001

    View details for PubMedID 9832025

  • Predictors of aneurysmal occlusion in the period immediately after endovascular treatment with detachable coils: A multivariate analysis Annual Meeting of the American-Society-of-Neuroradiology Turjman, F., Massoud, T. F., Sayre, J., Vinuela, F. AMER SOC NEURORADIOLOGY. 1998: 1645–51


    Complete intracranial aneurysmal occlusion by endovascular techniques is required for successful treatment and is presumably influenced by several parameters. The purpose of this study was to investigate whether operator experience and angiographic characteristics of intracranial aneurysms correspond to the degree of endovascular occlusion in the period immediately after treatment with Guglielmi detachable coils (GDCs).Pre- and posttreatment angiograms of 72 patients undergoing GDC treatment were reviewed retrospectively. The following angiographic characteristics of the aneurysms were evaluated: largest diameter of the sac, volume, neck size, shape, type, cerebrovascular site, surroundings, and likely direction of aneurysmal inflow as judged by a score developed by measuring aneurysm/parent artery angulation. The chronological sequence in which the aneurysms were treated was used as a measure of operator experience. A chi2-test was used to identify parameters that correlated with outcomes of total (100%) or partial (<100%) occlusion. A multivariate analysis was used to determine the factors most predictive of aneurysmal occlusion at therapy.Parameters that correlated with the unsatisfactory result of partial occlusion were large aneurysmal diameter, volume, and neck size, more direct inflow (ie, increasingly obtuse aneurysm/parent artery angulation), and early chronological presentation in the series. The three factors most predictive of partial occlusion were large aneurysmal diameter, more direct inflow, and early chronological order of treatment.Several morphologic features of aneurysms were identified to help predict the immediate outcome of occlusion with GDCs. This study underscores the existence of a steep learning curve associated with GDC use in treating aneurysms and the importance of operator experience in achieving optimal therapeutic results.

    View details for Web of Science ID 000076452600013

    View details for PubMedID 9802486

  • Hemodynamic changes in arterial feeders and draining veins during embolotherapy of arteriovenous malformations: An experimental study in a swine model NEUROSURGERY Murayama, Y., Massoud, T. F., Vinuela, F. 1998; 43 (1): 96-104


    Transcatheter assessment of changes in draining vein (DV) flow velocity has been proposed recently as a potentially useful procedure for hemodynamic monitoring of the progression of embolotherapy in cerebral arteriovenous malformations (AVMs). We compared and contrasted changes in hemodynamic parameters of arterial feeders (AFs) and DVs during experimental AVM embolotherapy.Carotid-jugular fistula-type AVM models were surgically created in eight swine. Pre- and postembolization transcatheter mean AF and DV pressures, DV-time average spectral peak velocity, and AF and DV pulsatility indices were assessed. An expression, the peak systolic velocity minus end-diastolic velocity (Vs - Ved), was also used in evaluating the transvenous Doppler spectra. Pre- and postembolization hemodynamic parameters were compared statistically.Pre-embolization DV flow was pulsatile (Vs - Ved, 12 +/- 4.8 cm/s), with a mean DV velocity of 39.3 +/- 11.4 cm per second. Postembolization, this changed to a less/nonpulsatile pattern (Vs - Ved, 5.4 +/- 2.7 cm/s; P = 0.0035) with a lower mean DV-average spectral peak velocity of 7.0 +/- 3.1 cm per second (P = 0.0001). The mean DV pressure was also reduced from 52.0 +/- 8.2 to 45.5 +/- 8.7 mm Hg (P = 0.0023). The mean AF pressure increased from a mean of 79.5 +/- 15.5 to 96.8 +/- 16.2 mm Hg (P = 0.0004). The DV pulsatility index values also increased from a mean of 0.3 +/- 0.2 to 1.1 +/- 0.5 (P = 0.0003). Periembolization objective hemodynamic changes were detected in the DVs earlier than were the visually subjective angiographic changes observed within the nidus.This preliminary study indicates that transvenous assessment of average spectral peak velocity and wave pattern (Vs - Ved) may be useful in the hemodynamic evaluation of AVM shunting. The convergence of these two parameters to a range less than 10 cm per second after nidus embolization may afford a theoretical advantage over AF pressure measurements when used for objective and quantitative monitoring of endovascular embolotherapy.

    View details for Web of Science ID 000074274500057

    View details for PubMedID 9657195

  • Ion Implantation Modifies the Surface of GDCs. An Experimental Study in Swine Aneurysms. Interventional neuroradiology Murayama, Y., Viñuela, F., Suzuki, Y., Massoud, T. F., Guglielmi, G., Iwaki, M., Kamio, M., Abe, T. 1997; 3: 156-161


    Summary: Ion implantation and protein-coatings were utilized to alter the surface properties (endothelial cellular adhesion) and enhance the thrombogenicity of Guglielmi detachable coils (GDCs) for endovascular treatment of cerebral aneurysms. These modified GDCs were compared with standard GDCs in the treatment of experimental swine aneurysms. Standard GDCs and ion-implanted protein coated GDCs were used to treat 32 aneurysms in 16 swine. GDCs were coated with either proteins, collagen (n=5), vitronectin (n=4), fibrinogen (Fn=3), laminin (n=2), or fibronectin (n=2) and underwent Ne(+) or He(+) implantation with a fluence of 1 x 10(14--) 10(15) ions/cm(2) at an energy of 150 keV. Bilateral experimental swine aneurysms were embolized with standard GDCs (n=16) on one side and with ion-implanted proteincoated GDCs (n=16; total) on the other side. The necks of aneurysms were evaluated macroscopically and histopathologically at autopsy using day 14 posttreatment specimens. Greater fibrous coverage of the necks of aneurysms were observed in the ion-implanted coil group. The results of this experimental study indicate that Ion implantation combined with protein coating of GDCs improved cellular adhesion and proliferation. Future application of this technology may provide early wound healing at the necks of embolized widenecked cerebral aneurysms.

    View details for PubMedID 20678409

  • A nonlinear quasi-static model of intracranial aneurysms NEUROLOGICAL RESEARCH Chitanvis, S. M., Dewey, M., Hademenos, G., Powers, W. J., Massoud, T. F. 1997; 19 (5): 489-496


    Biomathematical models of intracranial aneurysms can provide qualitative and quantitative information on stages of aneurysm development through elucidation of biophysical interactions and phenomena. However, most current aneurysm models, based on Laplace's law, are renditions of static, linearly elastic spheres. The primary goal of this study is to: 1. develop a nonlinear constitutive quasi-static model and 2. derive an expression for the critical size/pressure of an aneurysm, with subsequent applications to clinical data. A constitutive model of an aneurysm, based on experimental data of tissue specimens available in the literature, was incorporated into a time-dependent set of equations describing the dynamic behavior of a saccular aneurysm in response to pulsatile blood flow. The set of differential equations was solved numerically, yielding mathematical expressions for aneurysm radius and pressure. This model was applied to clinical data obtained from 24 patients presenting with ruptured aneurysms. Aneurysm development and eventual rupture exhibited an inverse relationship between aneurysm size and blood pressure. In general, the model revealed that rupture becomes highly probable for an aneurysm diameter greater than 2.0 mm and a systemic blood pressure greater than 125 mmHg. However, an interesting observation was that the critical pressure demonstrated a minimal sensitivity to the critical radius, substantiating similar clinical and experimental observations that blood pressure was not correlated, to any degree, with aneurysm rupture. Undulations in the aneurysm wall, presented by irregular multilobulated morphologies, could play an important role in aneurysm rupture. However, due to the large variation in results, more extensive studies will be necessary for further evaluation and validation of this model.

    View details for Web of Science ID A1997YF24900004

    View details for PubMedID 9329025

  • Biophysical mechanisms of stroke STROKE Hademenos, G. J., Massoud, T. F. 1997; 28 (10): 2067-2077


    Stroke is the third leading cause of death and the leading cause of long-term disability in the United States. Although a host of genetic, biochemical, physiological, anatomic, and histological factors have been implicated, to varying degrees, in the pathogenesis of stroke, biophysical factors are believed to play a significant role in the development, diagnosis, and therapy of stroke. The purpose of this review article is to identify, describe, and illustrate these causes and biophysical and hemodynamic mechanisms predisposing a person to stroke, which often form the basis for novel methods of diagnosis and therapy.This mini-review begins by describing the physical principles that govern the flow of blood through normal and stenosed carotid artery bifurcations. In addition to the tortuosity, curvature, and tensile forces of the carotid artery bifurcation, the effects of biophysical phenomena from flowing blood such as viscous forces, pressure forces, velocity, kinetic energy, momentum, impulse, shear stress, and vibrational displacements exerted by the flowing blood on the vessel wall are conducive to abnormal flow behavior and patterns, degrading the vessel wall and creating the potential for stroke.Recent advances in the treatment of stroke are based on increasing knowledge of its underlying biophysical mechanisms, as well as on better-publicized advances in imaging instrumentation and procedures for the management and treatment of patients.

    View details for Web of Science ID A1997YD02500046

    View details for PubMedID 9341720

  • Experimental study of treatment of aneurysm by vascular endoprosthesis JOURNAL OF NEURORADIOLOGY Turjman, F., Acevedo, G., Massoud, T. F., Moll, T., Sindou, M., Guglielmi, G., Vinuela, F., Froment, J. C. 1997; 24 (3): 205-211


    Intracranial aneurysms occur frequently with the risk of major damage. Neurosurgery or endovascular techniques can be used for treatment. Current techniques are not well adapted for aneurysms with a wide implantation (or neck). The aim of this experimental work was to study a technique for treating aneurysms which can be used for wide neck aneurysms. A metal stent is implanted facing the neck of the aneurysm to allow occlusion. In the first part of the study, the stent was inserted alone. Ten aneurysms were created surgically in five dogs. The stents were positioned facing seven of the ten aneurysms. The stent led to immediate occlusion of the aneurysm in six of the cases. One aneurysm remained patent despite the correct position of the stent. One dog developed secondary thrombosis of the carotid. Three dogs have been followed for sixty days after insertion of the stent. Two aneurysms thrombosed and one was patent. Since these results were less than satisfactory, a second part of the study was undertaken to cover the stent with a fragment of the autologous vein. Results in five aneurysms, evaluated three and eight weeks after treatment, showed partial or total repermeabilization of the aneurysms. In the third part of the study, we associated stents and detachable coils. Twelve aneurysms of the carotid artery in pigs were thrombosed and two aneurysms were completely occluded after stent implantation. In the nine other cases, the aneurysms were completely occluded after stent implantation. In the nine other cases, the aneurysms remained patent despite the stent and treatment was then completed with a coil. Six of the animals have been followed for thirteen weeks. One carotid artery thrombosed. In the five other cases, the carotid arteries were patent and the aneurysms were occluded at the control angiogram. Histology results showed the presence of a fibromuscular endothelialized neointima at the neck of the aneurysm in four of the five cases. The technique described here could be proposed for the treatment of wide-neck aneurysms implanted low on the carotid artery in man. Improvements should render the system more flexible.

    View details for Web of Science ID A1997YD81000005

    View details for PubMedID 9417478

  • Ion implantation and protein coating of detachable coils for endovascular treatment of cerebral aneurysms: Concepts and preliminary results in swine models NEUROSURGERY Murayama, Y., Vinuela, F., Suzuki, Y., Do, H. M., Massoud, T. F., Guglielmi, G., Ji, C., Iwaki, M., Kusakabe, M., Kamio, M., Abe, T. 1997; 40 (6): 1233-1243


    Complete anatomic obliteration remains difficult to achieve with endovascular treatment of wide-necked aneurysms using Guglielmi detachable platinum coils (GDCs). Ion implantation is a physicochemical surface modification process resulting from the impingement of a high-energy ion beam. Ion implantation and protein coating were used to alter the surface properties (thrombogenicity, endothelial cellular migration, and adhesion) of GDCs. These modified coils were compared with standard GDCs in the treatment of experimental swine aneurysms.In an initial study, straight platinum coils were used to compare the acute thrombogenicity of standard and modified coils. Modified coils were coated with albumin, fibronectin, or collagen and underwent Ne+ ion implantation at a dose of 1 x 10(15) ions/cm2 and an energy of 150 keV. Coils were placed in common iliac arteries of 17 swine for 1 hour, to evaluate their acute interactions with circulating blood. In a second study, GDCs were used to treat 34 aneurysms in an additional 17 swine. GDCs were coated with fibronectin, albumin, collagen, laminin, fibrinogen, or vitronectin and then implanted with ions as described above. Bilateral experimental swine aneurysms were embolized with standard GDCs on one side and with ion-implanted, protein-coated GDCs on the other side. The necks of aneurysms were evaluated macroscopically at autopsy, by using post-treatment Day 14 specimens. The dimensions of the orifice and the white fibrous membrane that covered the orifice were measured as the fibrous membrane to orifice proportion. Histopathological evaluation of the neck region was performed by light microscopy and scanning electron microscopy.Fibronectin-coated, ion-implanted coils showed the greatest acute thrombogenicity (average thrombus weight for standard coils, 1.9 +/- 1.5 mg; weight for fibronectin-coated coils, 8.6 +/- 6.2 mg; P < 0.0001). By using scanning electron microscopy, an intensive blood cellular response was observed on ion-implanted coil surfaces, whereas this was rare with standard coils. At Day 14, greater fibrous coverage of the necks of aneurysms was observed in the ion-implanted coil group (mean fibrous membrane to orifice proportion of 69.8 +/- 6.2% for the ion-implanted coil group, compared with 46.8 +/- 15.9% for the standard coil group; P = 0.0143).The results of this preliminary experimental study indicate that ion implantation combined with protein coating of GDCs improved cellular adhesion and proliferation. Future application of this technology may provide early wound healing at the necks of embolized, wide-necked, cerebral aneurysms.

    View details for Web of Science ID A1997XC45000058

    View details for PubMedID 9179897

  • A new surface modification technique of platinum coils by ion implantation and protein coating: Use in intravascular treatment of brain aneurysms 10th International Conference on Ion Beam Modification of Materials (IBMM-96) Murayama, Y., Suzuki, Y., Vinuela, F., Massoud, T. F., Do, H. M., Guglielmi, G., Iwaki, M., Kamio, M., Abe, T. ELSEVIER SCIENCE BV. 1997: 1015–1018
  • Anatomical variants of the profunda femoris artery: An angiographic study SURGICAL AND RADIOLOGIC ANATOMY Massoud, T. F., Fletcher, E. W. 1997; 19 (2): 99-103


    The bifurcation of the common femoral artery (CFA) into superficial and profunda femoris arteries (PFA) and the branching pattern of the PFA are subject to considerable normal anatomical variation. These variation patterns were assessed on normal lower limb angiograms of 94 adult patients. The main pattern (in 81% of patients) consisted of both medial and lateral circumflex arteries arising directly from a PFA situated lateral or posterolateral to the femoral artery. Previous studies of arterial variations in this region and the relevant embryology are reviewed. Relevance to angiographic procedures of the lower limb is discussed.

    View details for Web of Science ID A1997XF23900009

    View details for PubMedID 9210243

  • An electrical network model of intracranial arteriovenous malformations: Analysis of variations in hemodynamic and biophysical parameters NEUROLOGICAL RESEARCH Hademenos, G. J., Massoud, T. F. 1996; 18 (6): 575-589


    The propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage is correlated significantly with their hemodynamic features. Biomathematical models offer a theoretical approach to analyse complex AVM hemodynamics, which otherwise are difficult to quantify, particularly within or in close proximity to the nidus. Our purpose was to investigate a newly developed biomathematical AVM model based on electrical network analysis in which morphological, biophysical, and hemodynamic characteristics of intracranial AVMs were replicated accurately. Several factors implemented into the model were altered systematically to study the effects of a possible wide range of normal variations in AVM hemodynamic and biophysical parameters on the behavior of this model and its fidelity to physiological reality. The model represented a complex, noncompartmentalized AVM with four arterial feeders, two draining veins, and a nidus consisting of 28 interconnected plexiform and fistulous components. Various clinically-determined experimentally-observed, or hypothetically-assumed values for the nidus vessel radii (plexiform: 0.01 cm-0.1 cm; fistulous: 0.1 cm-0.2 cm), mean systemic arterial pressure (71 mm Hg-125 mm Hg), mean arterial feeder pressures (21 mm Hg-80 mm Hg), mean draining vein pressures (5 mm Hg-23 mm Hg), wall thickness of nidus vessels (20 microns-70 microns), and elastic modulus of nidus vessels (1 x 10(4) dyn/cm2 to 1 x 10(5) dyn/cm2) were used as normal or realistic ranges of parameters implemented in the model. Using an electrical analogy of Ohm's law, flow was determined based on Poiseuille's law given the aforementioned pressures and resistance of each nidus vessel. Circuit analysis of the AVM vasculature based on the conservation of flow and voltage revealed the flow rate through each vessel in the AVM network. An expression for the risk of AVM nidus rupture was derived based on the functional distribution of the critical radii of component vessels. The two characteristics which were used to judge the fidelity of the theoretical performance of the AVM model against the physiological one of human AVMs were total volumetric flow through the AVM (< or = 900 ml/min), and its risk of rupture (< 100%). Applying these criteria, a series of 216 (out of 260) AVM models using different combinations of these hemodynamic and biophysical parameters resulted in a physiologically-realistic conduct of the model (yielding a total flow through the AVM model varying from 449.9 ml/min to 888.6 ml/min, and a maximum risk of rupture varying from 26.4 to 99.9%). The described novel biomathematical model characterizes the transnidal and intranidal hemodynamics of an intracranial AVM more accurately than previously possible. A wide range of hemodynamic and biophysical parameters can be implemented in this AVM model to result in simulation of human AVMs with differing characteristics (e.g. low-flow and high-flow AVMs). This experimental model should serve as a useful research tool for further theoretical investigations of a variety of intracranial AVMs and their hemodynamic sequelae.

    View details for Web of Science ID A1996VZ76500017

    View details for PubMedID 8985962

  • Arteriovenous malformation animal model for radiosurgery: The rete mirabile AMERICAN JOURNAL OF NEURORADIOLOGY DeSalles, A. A., Solberg, T. D., Mischel, P., Massoud, T. F., Plasencia, A., Goetsch, S., DeSouza, E., Vinuela, F. 1996; 17 (8): 1451-1458


    To study the effects of single-dose radiation on the porcine rete mirabile, a tangle of microvessels that mimics human arteriovenous malformations of the brain.Eight retia mirabilia received a single dose of radiation under stereotactic location with digital angiography and CT. The following doses were applied: 20, 30, 40, 50, 60, 70, 80, and 90 Gy. The animals were followed up for a period of 7 months. Findings at neurologic examination, serial angiography, and histopathologic examination were analyzed.Progressive occlusion as observed by angiography corresponded to the histopathologic finding of intimal hyperplasia; that is, marked thickening of the vessel wall, progressing to occlusion of the vascular lumen, and associated thrombosis. A direct dose response was noted for these changes. Neurologic findings were related to the dose distribution and to histologic findings in structures adjacent to the rete mirabile.The rete mirabile is an excellent model by which to study the radiologic and histologic effects of single-dose radiation to the microvasculature of the central nervous system.

    View details for Web of Science ID A1996VJ22000008

    View details for PubMedID 8883640

  • Endovascular treatment of arteriovenous malformations with selective intranidal occlusion by detachable platinum electrodes: Technical feasibility in a swine model AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Ji, C., Guglielmi, G., Vinuela, F. 1996; 17 (8): 1459-1466


    The technical feasibility of selective intranidal endovascular occlusion of experimental arteriovenous malformations with detachable superfine platinum electrodes was assessed in a swine model. The delivery and release of electrodes were performed within normal carotid retia mirabilia, the faster-flowing nidus (bilateral retia) of a carotid-jugular fistula-type model of an arteriovenous malformation, and a small-caliber H-type direct arteriovenous fistula. Controllable atraumatic placement of the electrodes was possible deep within each rete and in the middle of the fistula. The devices were soft and flexible, allowing them to conform to the tight turns and branches of rete vessels. Marked diminution of flow was achieved by release of multiple devices within each rete. Migration of the electrode occurred when detached within the larger-caliber arteriovenous fistula. The main advantages of this technique appear to be the controlled delivery and assured release of an occlusive radiopaque embolic agent within the nidus.

    View details for Web of Science ID A1996VJ22000009

    View details for PubMedID 8883641

  • Transvenous hemodynamic assessment of experimental arteriovenous malformations - Doppler guidewire monitoring of embolotherapy in a swine model STROKE Murayama, Y., Massoud, T. F., Vinuela, F. 1996; 27 (8): 1365-1372


    A Doppler guidewire was used to monitor progressive changes in draining vein flow parameters during experimental embolotherapy in a swine arteriovenous malformation (AVM) model.A microcatheter was positioned superselectively in the main arterial feeder and main draining vein in each of 10 AVM models in swine. With use of the Doppler guidewire, preembolization arterial and venous average peak velocities (APVs) and pulsatility indices were recorded. The device was left in the draining vein during transarterial particulate (in 8 swine) or liquid adhesive (in 2 swine) embolization, and continuous transvenous flow during and after treatment was monitored. Periembolization Doppler flow parameters were correlated qualitatively with angiographic changes in the nidus.Preembolization draining vein flow was pulsatile, with a mean APV of 38.9 +/- 13.7 cm/s. After embolization, this changed significantly to a less pulsatile or nonpulsatile pattern, with a lower mean APV of 9.2 +/- 4.9 cm/s (P = .0001). A novel expression, the maximum minus the minimum peak velocity (MxPV-MnPV), was used in evaluating the transvenous Doppler spectra. This was reduced significantly after embolization from a mean of 11.1 +/- 3.5 cm/s to 6.7 +/- 2.5 cm/s (P = .0025). Objective periembolization hemodynamic changes were detected in the draining veins earlier than the visually subjective angiographic changes within the nidus.Transvenous Doppler guidewire assessment of two parameters, APV and MxPV-MnPV, is useful in the hemodynamic evaluation of experimental arteriovenous shunting and may be used for future objective and quantitative monitoring during endovascular AVM embolotherapy.

    View details for Web of Science ID A1996VA09200020

    View details for PubMedID 8711804

  • Risk of intracranial arteriovenous malformation rupture due to venous drainage impairment - A theoretical analysis STROKE Hademenos, G. J., Massoud, T. F. 1996; 27 (6): 1072-1083


    Increased resistance in the venous drainage of intracranial arteriovenous malformations (AVMs) may contribute to their increased risk of hemorrhage. Venous drainage impairment may result from naturally occurring stenoses/occlusions, or if draining veins (DVs) undergo occlusion before feeding arteries during surgical removal, or after surgery in the presence of "occlusive hyperemia." We employed a detailed biomathematical AVM model using electrical network analysis to investigate theoretically the hemodynamic consequences and the risk of AVM rupture due to venous drainage impairment.The AVM model consisted of a noncompartmentalized nidus with 28 vessels (24 plexiform components and 4 fistulous components), 4 arterial feeders, and 2 DVs. An expression for the risk of AVM nidus rupture was derived on the basis of functional distribution of the critical radii of component vessels. Risk was calculated from biomathematical simulations of volumetric flow rate with both DVs patent and for four stages of venous drainage obstruction: (1) 25%, (2) 50%, (3) 75%, and (4) 100%. Each stage of occlusion was applied to each DV while the other DV was patent and then to the patent DV while the other DV was totally occluded.For flow through the AVM when both DVs were unobstructed, the baseline risk of AVM nidus rupture ranged from 4.4% to 91.2%. Theoretical rupture occurred in nidus components proximal to the DVs when the risk exceeded 100%, as was observed with the obstruction of DV1 and a patent DV2. The ranges for risk of rupture across the nidus for the four stages were (1) 4.7% to 90.5%, (2) 5.9% to 86.9%, (3) 0% to 98.4%, and (4) 0% to 106.3%, respectively. Rupture was observed for an 86% occlusion of DV1 (ie, the DV fed by the intranidal fistula) and DV2 patent, primarily because of the dramatic shift in the hemodynamic burden toward the weaker plexiform nidus vessels.On theoretical grounds, venous drainage impairment was predictive of AVM nidus rupture and was strongly dependent on AVM morphology (presence of intranidal fistulas and their spatial relation to DVs) and hemodynamics. Specifically, stenosis/occlusion of a high-flow DV induces a rapid redistribution of blood into the weak plexiform vessels of the opposing region of the nidus, causing a hemodynamic overload and an increased risk of rupture. These findings should be carefully considered among all factors affecting the natural history of intracranial AVMs and the mechanisms implicated in their spontaneous rupture. They may also provide a theoretical rationale for some of the hemorrhagic complications that occur during and after surgical treatment.

    View details for Web of Science ID A1996UP11900010

    View details for PubMedID 8650717

  • A biomathematical model of intracranial arteriovenous malformations based on electrical network analysis: Theory and hemodynamics NEUROSURGERY Hademenos, G. J., Massoud, T. F., Vinuela, F. 1996; 38 (5): 1005-1014


    Hemodynamics play a significant role in the propensity of intracranial arteriovenous malformations (AVMs) to hemorrhage and in influencing both therapeutic strategies and their complications. AVM hemodynamics are difficult to quantitate, particularly within or in close proximity to the nidus. Biomathematical models represent a theoretical method of investigating AVM hemodynamics but currently provide limited information because of the simplicity of simulated anatomic and physiological characteristics in available models. Our purpose was to develop a new detailed biomathematical model in which the morphological, biophysical, and hemodynamic characteristics of an intracranial AVM are replicated more faithfully. The technique of electrical network analysis was used to construct the biomathematical AVM model to provide an accurate rendering of transnidal and intranidal hemodynamics. The model represented a complex, noncompartmentalized AVM with 4 arterial feeders (with simulated pial and transdural supply), 2 draining veins, and a nidus consisting of 28 interconnecting plexiform and fistulous components. Simulated vessel radii were defined as observed in human AVMs. Common values were assigned for normal systemic arterial pressure, arterial feeder pressures, draining vein pressures, and central venous pressure. Using an electrical analogy of Ohm's law, flow was determined based on Poiseuille's law given the aforementioned pressures and resistances of each nidus vessel. Circuit analysis of the AVM vasculature based on the conservation of flow and voltage revealed the flow rate through each vessel in the AVM network. Once the flow rate was established, the velocity, the intravascular pressure gradient, and the wall shear stress were determined. Total volumetric flow through the AVM was 814 ml/min. Hemodynamic analysis of the AVM showed increased flow rate, flow velocity, and wall shear stress through the fistulous component. The intranidal flow rate varied from 5.5 to 57.0 ml/min with and average of 31.3 ml/min for the plexiform vessels and from 595.1 to 640.1 ml/min with an average of 617.6 ml/min for the fistulous component. The blood flow velocity through the AVM nidus ranged from 11.7 to 121.1 cm/s with an average of 66.4 cm/s for the plexiform vessels and from 446.9 to 480 dyne/cm2 with an average of 463.5 dyne/cm2 for the fistulous component. The wall shear stress ranged in magnitude from 33.2 to 342.1 dyne/cm2 with an average of 187.7 dyne/cm2 for the plexiform vessels and from 315.9 to 339.7 cm/s with an average of 327.8 cm/s for the fistulous component. The described novel biomathematical model characterizes the transnidal and intranidal hemodynamics of an intracranial AVM more accurately than was possible previously. This model should serve as a useful research tool for further theoretical investigations of intracranial AVMs and their hemodynamic sequelae.

    View details for Web of Science ID A1996UF56600060

    View details for PubMedID 8727827

  • Endovascular treatment of multiple aneurysms involving the posterior intracranial circulation AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Guglielmi, G., Vinuela, F., Duckwiler, G. R. 1996; 17 (3): 549-554


    The results of surgery on multiple intracranial aneurysms tha involve the vertebrobasilar circulation are poor, and associated patient mortality remains high. We describe the endovascular treatment of four patients with mutiple aneurysms that involved the posterior intracrancial circulation. Satisfactory occlusion of all aneurysms was achieved by using electrolytically detachable coils, and all patients had a good clinical recovery. Our early experience suggests that endovascular coil occlusion may be a particularly suitable method for treating this high-risk condition.

    View details for Web of Science ID A1996UB13900024

    View details for PubMedID 10200108

  • Laboratory simulations and training in endovascular embolotherapy with a swine arteriovenous malformation model AMERICAN JOURNAL OF NEURORADIOLOGY Massoud, T. F., Ji, C., Vinuela, F., Turjman, F., Guglielmi, G., Duckwiler, G. R., Gobin, Y. P. 1996; 17 (2): 271-279


    We assessed the suitability of a swine experimental arteriovenous malformation model for laboratory simulations and training in endovascular embolotherapy. Embolizations with liquid glue or particles were performed in 10 animals. The parameters of injection (microcatheter position, concentration and volume of embolic agent, injection rate) were deliberately varied to simulate results that may be observed in clinical practice. A range of successful and less desirable therapeutic outcomes or complications was simulated. In one model, intravascular mean blood pressure in the "terminal feeder" rose after "nidus" embolization, consistent with observations in feeders of cerebral arteriovenous malformations. Experience in the technical aspects of embolotherapy was gained by repeated performances using this model. Simplicity of creation, clear angiographic visibility of feeders, a nidus and a draining vein, and hemodynamic similarities with cerebral arteriovenous malformations make this an attractive in vivo experimental model for learning the principles of embolotherapy, testing new embolic agents, and training/gaining experience in embolization techniques.

    View details for Web of Science ID A1996TW23400019

    View details for PubMedID 8938298

  • Treatment of large and giant fusiform intracranial aneurysms with Guglielmi detachable coils JOURNAL OF NEUROSURGERY Gobin, Y. P., Vinuela, F., Gurian, J. H., Guglielmi, G., Duckwiler, G. R., Massoud, T. F., Martin, N. A. 1996; 84 (1): 55-62


    Results in nine patients with large or giant fusiform intracranial aneurysms that were treated with Guglielmi detachable coils (GDCs) are reported. There were six males and three females between the ages of 12 and 63. Four patients presented with subarachnoid hemorrhage (SAH) and four with mass effect; in one patient the aneurysm was asymptomatic and located in an arterial feeder of an arteriovenous malformation. Five aneurysms were supratentorial and four were in the posterior fossa. Five were giant and four were large. Selective occlusion with preservation of the parent artery was attempted in three cases, and complete occlusion of the aneurysm and the parent artery was performed in six patients. The tolerance to parent artery occlusion was assessed by angiography, balloon test occlusion, and amytal testing. Six aneurysms were permanently occluded and two partially recanalized. In one case, GDC embolization was not possible. The four patients who presented with SAH made an excellent clinical recovery. Three of the four patients presenting with mass effect recovered completely and one remained unchanged. The patient with an incidental aneurysm remained asymptomatic. There were no permanent complications. In conclusion, GDCs were useful for the occlusion of large and giant intradural fusiform aneurysms. Occlusion of the aneurysm and the parent artery afforded the greatest opportunity for a complete cure. Advantages of GDCs compared to balloons include: occlusion of a shorter segment of normal artery, no traction on the parent vessel, and safer and easier catheterization techniques.

    View details for Web of Science ID A1996TL44400009

    View details for PubMedID 8613836



    To assess the biomechanical feasibility of treating experimental fusiform aneurysms endovascularly with a combination of stents and coils.An experimental model was surgically constructed in the necks of nine swine to simulate intracranial fusiform aneurysms possessing important "perforators" or side branches. Balloon-expandable metal stents were positioned across the aneurysms in eight swine. In five of these, additional treatment was intraaneurysmal placement of detachable microcoils. Attempts were made to deposit these coils strategically away from the origin of the side branch.Stent placement was successful in seven swine but failed in one swine because of stent-aneurysm size mismatch. Two swine treated with only stents showed no significant alterations in blood filling of the aneurysm or side branch. Satisfactory coil placement (outside the stent, within the aneurysm sac, and away from the orifice of the side branch) was achieved in four of the five swine treated with stents and coils. Careful fluoroscopic monitoring and controlled coil delivery were necessary to avoid covering the sidebranch origin. These aneurysms could not be packed densely after detachment of the first coil because of the resultant radiographic overlap of multiple coil loops on the stent and its lumen in all projections. In one swine there was inadvertent untoward reentry of the coil tip into the expanded stent lumen during its delivery.Endovascular treatment of experimental fusiforms aneurysms using stents and coils is technically feasible. The stent maintains patency of the parent artery while allowing strategic coil placement in the aneurysm sac away from the origin of side branches. This technique may prove useful in the future treatment of intracranial fusiform aneurysms. However, potential sources of technical difficulties have been identified, and further longterm studies using an appropriate intracranial stent will be necessary before human application.

    View details for Web of Science ID A1995TF78300002

    View details for PubMedID 8585480



    Superselective angiography is the most accurate technique in the analysis of brain arteriovenous malformation (AVM) angioarchitecture. Therefore, we reviewed the selective and superselective angiograms of 100 consecutive patients with intracerebral AVMs. Our purpose was to determine which parameters of angioarchitecture were significantly correlated with a clinical presentation of hemorrhage. The vascular characteristics evaluated on the angiograms were the size of the AVM, the location of the AVM, the type of nidus, the type of feeders, the characteristics of venous drainage, and the number and location of aneurysms. The parameters found to correlate with hemorrhage were deep venous drainage (P = 0.01), feeding by perforators (P = 0.01), intranidal aneurysm(s) (P = 0.004), multiple aneurysms (P = 0.001), feeding by the vertebrobasilar system (P = 0.002), and location in the basal ganglia (P = 0.04). Six parameters of AVM angioarchitecture were correlated with a clinical presentation of hemorrhage. Among these parameters, three (feeding by perforators, number of aneurysms, and presence of intranidal aneurysms) were well displayed by superselective angiogram.

    View details for Web of Science ID A1995TC38100005

    View details for PubMedID 8559332



    Accurate measurement of the aneurysm neck size from diagnostic angiograms is crucial in the consideration and implementation of interventional embolotherapeutic procedures. Due to inherent problems in angiography, aneurysm morphology and location, and obstruction by overlying structures, accurate measurement of the aneurysm neck size is difficult. We are proposing a method for the angiographic measurement of aneurysm neck size based on a biomathematical model of an aneurysm. A biomathematical model of an intracranial saccular aneurysm was developed based on Laplace's law for a spherical elastic object, given by: Stress = Pressure x Radius/2 x Wall thickness. In addition, another biomechanical parameter used to describe an elastic sphere is the strain: Strain = delta R/Ri = (R-Ri)/Ri where R is the current aneurysm radius and Ri is the initial radius prior to aneurysm development. The stress and strain of an elastic structure are used to describe the elastic modulus, E: E = stress/strain = [PR/2h]/[(R-Ri)/Ri] = [PRRi]/[2hR-2hri]. It is assumed at this point that no additional tissue growth occurs through the developmental course of the aneurysm. The expression for E is now solved for Ri which, in essence, represents the radius of the aneurysm neck: Ri = [2hER]/[PR + 2hE]. Thus, the diameter of the neck, Dn, is given by Dn = 2 + i = 2 ([2hER]/[PR + 2hE]). During diagnostic angiography, the radius, R, and pressure, P, are easily obtained during the examination procedure. However, it is not possible to angiographically determine the elastic modulus, E, and the wall thickness, h. In this case, the following average values are used: E = 1.0 MPa and h = 50 microns. From the diagnostic angiograms and hospital records of 23 patients, the aneurysm neck size was determined using the biomathematical model and compared to the results obtained from the correlative relationship between the measured and accepted ratios of neck size to diameter of parent artery. The neck diameter as measured from the accepted ratios of neck size to parent artery diameter for the 23 patients ranged from 1.5 mm to 8.7 mm. The angiographically measured neck sizes were in excellent agreement with those obtained from the biomathematical model, particularly for the wide-necked aneurysms, as evidenced by the fact that all but two chi 2 values were < 1.0. We have described a simple yet accurate method for obtaining aneurysm neck size measurements from diagnostic angiograms using a biomathematical model. The model requires knowledge of only the aneurysm radius and blood pressure and becomes particularly important in characterizing wide-necked aneurysms.

    View details for Web of Science ID A1995TA93400001

    View details for PubMedID 8584121



    To evaluate the histologic and angiographic effects of collagen microbeads as an embolic agent in the swine rete mirabile.Human collagen particles (380 +/- 100 microns) of spheroidal shape and smooth surface were used to embolize the rete mirabile in five swine. Control angiograms and pathologic examinations were obtained immediately and sequentially from 3 to 35 days after embolization.The collagen particles were easy to inject through microcatheters. Embolization was always angiographically complete and persistent for at least 5 weeks. Histologic studies showed occlusion of 25% to 50% of the rete vessels. After 3 and 5 weeks' follow-up, transmural and adventitial chronic inflammation was present. Inflammatory infiltrates included lymphohistiocytic cells and scattered eosinophils. The foreign-body giant-cell reaction was pronounced. No evidence of angionecrosis or focal hemorrhage was shown.Collagen microbeads are a promising experimental embolic agent, with potential future applications in humans.

    View details for Web of Science ID A1995QX57800005

    View details for PubMedID 7639124



    We present a case of a young adult in whom acute subdural hemorrhage developed immediately after embolization of a cerebral arteriovenous malformation with glue. Inadvertent venous outlet obstruction with glue was implicated in the production of the hemorrhage. Possible mechanisms of spread of blood to the subdural space are discussed. Awareness of the possibility of iatrogenic subdural hemorrhage is necessary before undertaking embolization procedures.

    View details for Web of Science ID A1995QT86800012

    View details for PubMedID 7611056



    To identify the morphological vascular characteristics of cerebral arteriovenous malformations (AVMs) that predict a clinical presentation of epilepsy.Fifteen angioarchitectural characteristics of brain AVMs were selected for assessment in 100 consecutive patients referred to our institution for endovascular treatment. In this population, 47% of the AVMs were diagnosed as a consequence of epilepsy. The angioarchitectural characteristics and population demographics were statistically analyzed by means of multivariate analysis.The following six parameters were found to be the most predictive of epilepsy: cortical location of the AVM, feeding by the middle cerebral artery, cortical location of the feeder, absence of aneurysms, presence of varix/varices in the venous drainage, and association of varix and absence of intranidal aneurysms. Three factors were not among the most predictive factors of epilepsy but were significantly associated with the onset of seizures: AVM feeding by the external carotid artery, a temporal cortical location, and a parietal cortical location.Detailed analysis of the angioarchitecture of intracranial AVMs has helped us identify features that strongly correlate with epilepsy. This may aid in future understanding of the physiopathologic mechanisms in epilepsy associated with AVMs, and in identifying goals of treatment for epileptogenic AVMs.

    View details for Web of Science ID A1995QG57400019

    View details for PubMedID 7726084



    Laplace's law, which describes a linear relation between the tension and the radius, is often used to characterize the mechanical response of the aneurysm wall to distending pressures. However, histopathological studies have confirmed that the wall of the fully developed aneurysm consists primarily of collagen and is subject to large increases in tension for small increases in the radius, i.e., a nonlinear relationship exists between the tension within the aneurysm wall and the radius. Thus, a nonlinear version of Laplace's law is proposed to accurately describe the development and rupture of a fusiform saccular aneurysm. The fusiform aneurysm was modelled as a thin-walled ellipsoidal shell with a major axis radius, Ra, minor axis radius, Rb, circumferential tension, S0, and meridional tension, S phi, with phi defining the angle from the surface normal. Using both linear and nonlinear models, differential expressions of the volume distensibility evaluated at 90 degrees were used to determine the critical radius of the aneurysm along the minor axis from S0 and S phi in terms of the following geometric and biophysical variables; A, elastic modulus of collagen; E, elastic modulus of the aneurysm (elastin and collagen); t, wall thickness; P, systolic pressure; and Ra. For typical physiological values of A = 2.8 MPa, E = 1.0 MPa, T = 40 microns, P = 150 mmHg, and Ra = 4Rb, the linear model yielded critical radii of 4.0 mm from S phi and 2.2 mm from S0. The resultant critical radius was 4.56 mm. Using the same values, the critical radii from the tension components of the nonlinear model were 3.5 mm from S phi and 1.9 mm from S0.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1994PY78100006

    View details for PubMedID 7708133



    To report the comprehensive superselective angiographic characteristics of aneurysms associated with cerebral arteriovenous malformations.One hundred consecutive patients referred for cerebral arteriovenous malformation embolization underwent preembolization superselective angiography. Superselective angiograms were obtained after microcatheterization of arteriovenous malformation pedicles, and assessed for number and location of aneurysms related to the malformation. A chi 2 test was conducted to correlate these parameters with the onset of intracranial hemorrhage.Aneurysms were demonstrated in 58 of 100 patients. Single aneurysms were found in 24 patients and multiple aneurysms in 34. Presence and number of aneurysms were found to correlate significantly with a clinical presentation of hemorrhage.Superselective angiography was found to be of paramount importance in elucidating the precise and detailed angioarchitecture of brain arteriovenous malformations.

    View details for Web of Science ID A1994PL56400001

    View details for PubMedID 7847201



    Experimental models of intracranial saccular aneurysms are a useful contribution to our basic understanding of these lesions. Currently, the commonest in use are those constructed surgically in laboratory animals. We review the numerous surgical techniques available since the 1950s, and the research applications and uses of experimental aneurysms. Further development and use of such models is greatly encouraged in future pathophysiological, hemodynamic, and therapeutic investigations of intracranial saccular aneurysms.

    View details for Web of Science ID A1994PL58000011

    View details for PubMedID 7845579



    Mathematical models of aneurysms are typically based on Laplace's law which defines a linear relation between the circumferential tension and the radius. However, since the aneurysm wall is viscoelastic, a nonlinear model was developed to characterize the development and rupture of intracranial spherical aneurysms within an arterial bifurcation and describes the aneurysm in terms of biophysical and geometric variables at static equilibrium. A comparison is made between mathematical models of a spherical aneurysm based on linear and nonlinear forms of Laplace's law. The first form is the standard Laplace's law which states that a linear relation exists between the circumferential tension, T, and the radius, R, of the aneurysm given by T = PR/2t where P is the systolic pressure. The second is a 'modified' Laplace's law which describes a nonlinear power relation between the tension and the radius defined by T = ARP/2At where A is the elastic modulus for collagen and t is the wall thickness. Differential expressions of these two relations were used to describe the critical radius or the radius prior to aneurysm rupture. Using the standard Laplace's law, the critical radius was derived to be Rc = 2Et/P where E is the elastic modulus of the aneurysm. The critical radius from the modified Laplace's law was R = [2Et/P]2At/P. Substituting typical values of E = 1.0 MPa, t = 40 microns, P = 150 mmHg, and A = 2.8 MPa, the critical radius is 4.0 mm using the standard Laplace's law and 4.8 mm for the modified Laplace's law.(ABSTRACT TRUNCATED AT 250 WORDS)

    View details for Web of Science ID A1994PP00800008

    View details for PubMedID 7870277

  • EXPERIMENTAL SACCULAR ANEURYSMS .2. A NEW MODEL IN SWINE NEURORADIOLOGY Guglielmi, G., Ji, C., Massoud, T. F., Kurata, A., Lownie, S. P., Vinuela, F., Robert, J. 1994; 36 (7): 547-550


    A new technique for surgical construction of experimental lateral saccular aneurysms on the common carotid artery of swine is described. It involves end-to-side suturing of an isolated segment of vein to an artery. During a short period of parent artery clamping, an elliptical arteriotomy is fashioned through the open-ended vein graft, the open end of which is subsequently tied and clamps are removed to form an aneurysmal vein pouch. The principal advantage of this technique is the short period of vascular clamping necessary to isolate a segment of the parent artery. This prevents severe endothelial injury and prolonged postoperative vasospasm, both of which may promote intra-aneurysmal thrombosis. Narrow- or wide-necked aneurysms can be created. Steps in the surgical construction of this model are detailed, and specific advantages of using swine are highlighted.

    View details for Web of Science ID A1994PL58000012

    View details for PubMedID 7845580



    Moyamoya disease (MMD) often presents with subarachnoid hemorrhage due to rupture of saccular aneurysms. We describe three patients with cerebrovascular features of MMD in whom four aneurysms of the posterior circulation were endovascularly occluded by electrothrombosis using the recently developed Guglielmi electrically detachable coils (GDC). Near total occlusion was achieved in three aneurysms. Subtotal occlusion was achieved in one aneurysm. This patient developed complications related to the neuroleptic anesthesia administered for the procedure. The particular hazards of anesthesia and aneurysmal surgery in MMD are discussed, and comparison is made with the benefits of using the GDC. Initial experience suggests that this endovascular approach is safe and effective in the treatment of saccular aneurysms in MMD. However, follow-up is necessary to assess long-term persistence of aneurysm obliteration.

    View details for Web of Science ID A1994PC46000008

    View details for PubMedID 8059323



    To assess the feasibility of combining stent implantation in the parent artery with endosaccular coil placement for the treatment of experimentally created wide-necked aneurysms.Wide-necked aneurysms were surgically created on the common carotid artery in 12 swine. A metal stent was endovascularly implanted across each aneurysm neck and its effect documented anigiographically. If the aneurysm remained patent, a microcatheter was introduced into the aneurysm through the stent mesh. Electrically detachable coils were delivered into the aneurysm sac to produce thrombosis.After stent implantation, one carotid artery thrombosed and two aneurysms spontaneously occluded. In the other 9 cases, coils were deposited through the stent to occlude the aneurysm. Complete aneurysm packing was possible in all 9 cases. The presence of the stent allowed placement of small coils near the aneurysm neck, thus contributing to the safe occlusion of small remnants in the final stages of aneurysm packing.The combination of stent implantation and coil placement is feasible in the treatment of experimental wide-necked saccular aneurysms. The stent maintains patency of the parent artery while allowing aneurysm occlusion by endosaccular coil placement through the stent's mesh. Occlusion of small aneurysm remnants is possible with no fear of coil hernation or migration into the parent artery. Long-term studies will be necessary before application to treatment of selected intracranial aneurysms.

    View details for Web of Science ID A1994NQ52800012

    View details for PubMedID 8073977



    We report our preliminary experience in the surgical construction of five experimental bifurcation and terminal aneurysm models in swine. We used unilateral neck vessels to construct models in which the relative directions and sizes of the parent and daughter arteries could be varied by surgery, resulting in aneurysms with high morphologic similarity to human intracranial lesions. Steps in the construction of each model are detailed.

    View details for Web of Science ID A1994NL03200021

    View details for PubMedID 8059664


    View details for Web of Science ID A1994NE39600011

    View details for PubMedID 8041445



    Sodium picosulphate (Picolax) is widely used for bowel preparation prior to colonic investigation or surgery. The most troublesome side effect reported is headache, which has been thought to be due to dehydration. In a prospective randomized study we investigated the incidence of adverse effects in patients given Picolax prior to barium enema examination, and assessed the incidence of adverse effects with different oral fluid regimens. A total of 197 outpatients were allocated to one of five fluid regimens on the day prior to the enema: (a) 4 pints of Dioralyte (glucose and electrolyte solution); (b) 4 pints of half-strength Dioralyte; (c) 4 pints of water; (d) 6 pints of water; and (e) free fluids. In a questionnaire, 36% of patients had no headache (graded 0/5), while 38% had a significant headache (graded 3/5 or greater). Sixteen per cent had significant abdominal pain, 42% had dry mouths, 43% thirst and 34% tiredness or irritability. There was no correlation between headache and fluid regimen. Furthermore, we have found no evidence of dehydration. None of the five fluid regimens was shown to offer any advantage, and we therefore recommend that patients be allowed to drink according to thirst when taking Picolax.

    View details for Web of Science ID A1994MP40300007

    View details for PubMedID 8299330



    Nasolacrimal duct obstruction and consequent epiphora is a complication that may develop in some patients following paranasal sinus surgery. We describe the technique of CT-dacryocystography which entails contrast injection of the lacrimal system and simultaneous computed tomography (CT) scanning of the facial structures. This technique provides concurrent information regarding obstruction of the nasolacrimal duct and the presence of disease recurrence or persistence in the adjacent paranasal sinuses. The role of CT-dacryocystography prior to endoscopic dacryocystorhinostomy is discussed briefly.

    View details for Web of Science ID A1993KR16900007

    View details for PubMedID 8472115



    A search of the literature suggests that the conventional 20 mg dose of intravenous hyoscine-N-butylbromide (HBB) for smooth muscle relaxation in double-contrast barium meal (DCBM) studies is largely empirical. This study analysed the merits of three different doses (5 mg, 10 mg, 20 mg) in the performance of routine DCBMs. One hundred and twenty DCBM examinations were prospectively and randomly allocated to receive one of three doses. Three parameters were measured for each examination: gastroduodenal distension, delay in gastric emptying and gastric antrum overlapping with barium-filled duodenal loops. Almost half the examinations using 5 mg produced undesirable duodenal-gastric overlay. Unacceptable early flooding of the duodenal bulb with barium was seen mostly with doses of 5 mg and 10 mg. Overall, the best results were obtained with 20 mg. The continued use of 20 mg HBB in routine DCBMs is recommended.

    View details for Web of Science ID A1992JW52700010

    View details for PubMedID 1464208

  • SEGMENTAL REVERSAL OF INTRAHEPATIC PORTAL FLOW DUE TO A LIVER METASTASIS BRITISH JOURNAL OF RADIOLOGY Kishimoto, R., Choji, K., Massoud, T. F., Matsuoka, S., Chen, M. H., Fujita, N., IRIE, G. 1992; 65 (779): 1035-1038

    View details for Web of Science ID A1992JY78000016

    View details for PubMedID 1450819

  • Case report: taste of success in thyroglossal fistulography. Clinical radiology Massoud, T. F., Schnetler, J. F. 1992; 45 (4): 281-283


    Thyroglossal fistulography is poorly documented in the radiological literature. An illustrative case is presented, highlighting the technique employed and the significance of its findings. The taste of contrast medium as it spills over the tongue is a useful additional sign in the successful demonstration of a fistulous communication. The contribution of fistulography to the accurate diagnostic work-up of patients undergoing the Sistrunk procedure is discussed.

    View details for PubMedID 1395390



    Subarachnoid hemorrhage due to spontaneous dissection of intracranial vessels is uncommon. Most such cases are confined to the posterior circulation. Dissection of an intracranial carotid artery producing subarachnoid hemorrhage without a focal ischemic event is rarely documented. We report a case and review the subject.

    View details for Web of Science ID A1992HD62000008

    View details for PubMedID 1553035


    View details for Web of Science ID A1991GR98500016

    View details for PubMedID 1756754



    Colonic carcinomas may be missed on the barium enema examination for a variety of perceptive, technical, and interpretive reasons. We report an uncommon source of error-persistent bowel spasm resulting in concealment of an underlying carcinoma. Awareness of this association is necessary in the effort to minimize diagnostic pitfalls of the barium enema examination.

    View details for Web of Science ID A1991FR53800014


    View details for Web of Science ID A1991EZ89100023

    View details for PubMedID 2043198



    The radiographs of 60 patients having double-contrast barium meal examinations were analysed by a linear analogue technique to assess variation in the quality of mucosal coating between morning and afternoon studies. No significant difference (P greater than 0.5) was found between morning and afternoon gastric mucosal coating. Factors that could in theory contribute to a diurnal variation are discussed. We conclude that afternoon DCBMs can be confidently booked and performed, in the knowledge that their diagnostic quality is not impaired.

    View details for Web of Science ID A1990EK74600005

    View details for PubMedID 2261719

  • Comment on the article by Barloon et al, in which hemodilution was found to occur after enteroclysis in patients with partial small bowel obstruction. Investigative radiology Massoud, T. F., Nolan, D. J. 1990; 25 (9): 1066-?

    View details for PubMedID 2211052

  • Treatment guidelines for early postoperative small bowel obstruction. Annals of surgery Massoud, T. F. 1990; 212 (1): 121-?

    View details for PubMedID 2363598


    View details for Web of Science ID A1990CV27100060

    View details for PubMedID 2315500


    View details for Web of Science ID A1990CN49100023

    View details for PubMedID 2340009