Professional Education


  • Postdoctoral Research Fellow, Stanford University, Radiology (2015)
  • Residency, Hospital of Technical University Munich, Germany, Anesthesiology (2012)
  • Doctor of Medicine, Ludwig Maximilian Universitat Munchen (2011)

Stanford Advisors


All Publications


  • Ferumoxytol Is Not Retained in Kidney Allografts in Patients Undergoing Acute Rejection. Molecular imaging and biology Aghighi, M., Pisani, L., Theruvath, A. J., Muehe, A. M., Donig, J., Khan, R., Holdsworth, S. J., Kambham, N., Concepcion, W., Grimm, P. C., Daldrup-Link, H. E. 2017

    Abstract

    To evaluate whether ultrasmall superparamagnetic iron oxide nanoparticle (USPIO)-enhanced magnetic resonance imaging (MRI) can detect allograft rejection in pediatric kidney transplant patients.The USPIO ferumoxytol has a long blood half-life and is phagocytosed by macrophages. In an IRB-approved single-center prospective clinical trial, 26 pediatric patients and adolescents (age 10-26 years) with acute allograft rejection (n = 5), non-rejecting allografts (n = 13), and normal native kidneys (n = 8) underwent multi-echo T2* fast spoiled gradient-echo (FSPGR) MRI after intravenous injection (p.i.) of 5 mg Fe/kg ferumoxytol. T2* relaxation times at 4 h p.i. (perfusion phase) and more than 20 h p.i. (macrophage phase) were compared with biopsy results. The presence of rejection was assessed using the Banff criteria, and the prevalence of macrophages on CD163 immunostains was determined based on a semi-quantitative scoring system. MRI and histology data were compared among patient groups using t tests, analysis of variance, and regression analyses with a significance threshold of p < 0.05.At 4 h p.i., mean T2* values were 6.6 ± 1.5 ms for native kidneys and 3.9 ms for one allograft undergoing acute immune rejection. Surprisingly, at 20-24 h p.i., one rejecting allograft showed significantly prolonged T2* relaxation times (37.0 ms) compared to native kidneys (6.3 ± 1.7 ms) and non-rejecting allografts (7.6 ± 0.1 ms). Likewise, three additional rejecting allografts showed significantly prolonged T2* relaxation times compared to non-rejecting allografts at later post-contrast time points, 25-97 h p.i. (p = 0.008). Histological analysis revealed edema and compressed microvessels in biopsies of rejecting allografts. Allografts with and without rejection showed insignificant differences in macrophage content on histopathology (p = 0.44).After ferumoxytol administration, renal allografts undergoing acute rejection show prolonged T2* values compared to non-rejecting allografts. Since histology revealed no significant differences in macrophage content, the increasing T2* value is likely due to the combined effect of reduced perfusion and increased edema in rejecting allografts.

    View details for DOI 10.1007/s11307-017-1084-8

    View details for PubMedID 28411307

  • How to Provide Gadolinium-Free PET/MR Cancer Staging of Children and Young Adults in Less than 1 h: the Stanford Approach. Molecular imaging and biology : MIB : the official publication of the Academy of Molecular Imaging Muehe, A. M., Theruvath, A. J., Lai, L., Aghighi, M., Quon, A., Holdsworth, S. J., Wang, J., Luna-Fineman, S., Marina, N., Advani, R., Rosenberg, J., Daldrup-Link, H. E. 2017

    Abstract

    To provide clinically useful gadolinium-free whole-body cancer staging of children and young adults with integrated positron emission tomography/magnetic resonance (PET/MR) imaging in less than 1 h.In this prospective clinical trial, 20 children and young adults (11-30 years old, 6 male, 14 female) with solid tumors underwent 2-deoxy-2-[(18)F]fluoro-D-glucose ([(18)F]FDG) PET/MR on a 3T PET/MR scanner after intravenous injection of ferumoxytol (5 mg Fe/kg) and [(18)F]FDG (2-3 MBq/kg). Time needed for patient preparation, PET/MR image acquisition, and data processing was compared before (n = 5) and after (n = 15) time-saving interventions, using a Wilcoxon test. The ferumoxytol-enhanced PET/MR images were compared with clinical standard staging tests regarding radiation exposure and tumor staging results, using Fisher's exact tests.Tailored workflows significantly reduced scan times from 36 to 24 min for head to mid thigh scans (p < 0.001). These streamlined PET/MR scans were obtained with significantly reduced radiation exposure (mean 3.4 mSv) compared to PET/CT with diagnostic CT (mean 13.1 mSv; p = 0.003). Using the iron supplement ferumoxytol "off label" as an MR contrast agent avoided gadolinium chelate administration. The ferumoxytol-enhanced PET/MR scans provided equal or superior tumor staging results compared to clinical standard tests in 17 out of 20 patients. Compared to PET/CT, PET/MR had comparable detection rates for pulmonary nodules with diameters of equal or greater than 5 mm (94 vs. 100 %), yet detected significantly fewer nodules with diameters of less than 5 mm (20 vs 100 %) (p = 0.03). [(18)F]FDG-avid nodules were detected with slightly higher sensitivity on the PET of the PET/MR compared to the PET of the PET/CT (59 vs 49 %).Our streamlined ferumoxytol-enhanced PET/MR protocol provided cancer staging of children and young adults in less than 1 h with equivalent or superior clinical information compared to clinical standard staging tests. The detection of small pulmonary nodules with PET/MR needs to be improved.

    View details for DOI 10.1007/s11307-017-1105-7

    View details for PubMedID 28721605

  • Safety Report of Ferumoxytol for Magnetic Resonance Imaging in Children and Young Adults INVESTIGATIVE RADIOLOGY Muehe, A. M., Feng, D., von Eyben, R., Luna-Fineman, S., Link, M. P., Muthig, T., Huddleston, A. E., Neuwelt, E. A., Daldrup-Link, H. E. 2016; 51 (4): 221-227

    Abstract

    The aim of this study was to assess the safety profile of ferumoxytol as an intravenous magnetic resonance imaging contrast agent in children.We prospectively evaluated the safety of ferumoxytol administrations as an "off-label" contrast agent for magnetic resonance imaging in nonrandomized phase 4 clinical trials at 2 centers. From September 2009 to February 2015, 49 pediatric patients (21 female and 28 male, 5-18 years) and 19 young adults (8 female and 11 male, 18-25 years) were reported under an investigator-initiated investigational new drug investigation with institutional review board approval, in health insurance portability and accountability act compliance, and after written informed consent of the child's legal representative or the competent adult patient was obtained. Patients received either a single dose (5 mg Fe/kg) or up to 4 doses of ferumoxytol (0.7-4 mg Fe/kg) intravenously, which were approximately equivalent to one third of the dose for anemia treatment. We monitored vital signs and adverse events directly for up to 1 hour after injection. In addition, we examined weekly vitals, hematologic, renal, and liver serum panels for 1 month after injection in over 20 pediatric patients. At fixed time points before and after ferumoxytol injection, data were evaluated for significant differences by a repeated measures linear mixed model.Four mild adverse events, thought to be related to ferumoxytol, were observed within 1 hour of 85 ferumoxytol injections: 2 episodes of mild hypotension and 1 case of nausea in 65 injections in pediatric patients without related clinical symptoms. One young adult patient developed warmness and erythema at the injection site. All adverse events were self-resolving. No spontaneous serious adverse events were reported. At a dose of 5 mg Fe/kg or lower, intravenous ferumoxytol injection had no clinical relevance or statistically significant effect (P > 0.05) on vital signs, hematological parameters, kidney function, or liver enzymes within 1 month of the injection.Ferumoxytol was overall well tolerated among 49 pediatric and 19 young adult patients experiencing various tumors or kidney transplants without major adverse events or signs of hematologic and kidney impairment or liver toxicity. Larger studies are needed to determine the incidence of anaphylactic reactions.

    View details for DOI 10.1097/RLI.0000000000000230

    View details for Web of Science ID 000372451200002

    View details for PubMedCentralID PMC4783197