Clinical Focus

  • Diagnostic Radiology

Professional Education

  • Board Certification: American Board of Radiology, Diagnostic Radiology (2016)
  • Fellowship: Stanford University Hospital (2016) CA
  • Internship: Kaiser Permanente Oakland Internal Medicine Residency (2011) CA
  • Medical Education: University of California at San Francisco School of Medicine (2010) CA
  • Residency: Stanford University Hospital (2015) CA
  • Residency: Mallinckrodt Institute of Radiology Washington University (2012) MO
  • Fellowship, Stanford University Hospital, Body MRI (2016)

All Publications

  • Reply: Is lifestyle modification effective for individuals with high fibrosis-4 index without an additional 2nd tier test? Hepatology (Baltimore, Md.) Sangha, K., Chang, S. T., Cheung, R., Deshpande, V. S. 2023

    View details for DOI 10.1097/HEP.0000000000000510

    View details for PubMedID 37300380

  • Reply: modeling concerns. Hepatology (Baltimore, Md.) Sangha, K., Chang, S. T., Cheung, R., Deshpande, V. S. 2023

    View details for DOI 10.1097/HEP.0000000000000446

    View details for PubMedID 37166119

  • Assessment of T2-weighted Image Quality at Prostate MRI in Patients with and Those without Intramuscular Injection of Glucagon. Radiology. Imaging cancer Sundaram, K. M., Rosenberg, J., Syed, A. B., Chang, S. T., Loening, A. M. 2023; 5 (3): e220070


    Purpose To assess whether administration of intramuscular (IM) glucagon improves T2-weighted image quality at multiparametric MRI (mpMRI) of the prostate. Materials and Methods In this Health Insurance Portability and Accountability Act-compliant single-center study, the authors retrospectively analyzed radiology reports from 3960 mpMRI examinations (2495 after exclusions) performed between September 2013 and September 2019 and performed outcome comparisons and semiquantitative image assessment of axial T2-weighted images from 120 consecutive mpMRI examinations performed between May 2015 and February 2016. Three experienced radiologists blinded to administration of IM glucagon assessed images using a five-point Likert scale (5 = no motion or blur) for overall image quality, anatomic delineation (prostate capsule, rectum, and lymph nodes), and identification of benign prostatic hyperplasia nodules. Wilcoxon rank sum and χ2 tests were used to assess quantitative parameters. Results The number of mpMRI radiology reports (599 examinations performed with glucagon; 1896, without glucagon) mentioning blur or motion were similar between groups (P = .82). Regression analysis of semiquantitative image quality assessments of T2-weighted images from mpMRI examinations (60 performed with glucagon; 60, without glucagon) demonstrated that images with glucagon were more likely to receive higher scores (4 or 5 rating) than those without glucagon only when the rectum (P = .001) and lymph nodes (P = .01) were evaluated, not when the prostatic capsule, benign prostatic hyperplasia nodules, or overall image quality was evaluated. No evidence of differences was found in identified Prostate Imaging Reporting and Data System (PI-RADS) lesions or targeted-biopsy Gleason scores. Conclusion Administration of IM glucagon did not improve T2-weighted image quality in prostate MRI examinations and showed similar PI-RADS scores and biopsy yields compared with examinations without glucagon. Keywords: MRI, Genital/Reproductive, Urinary, Prostate, Oncology, Observer Performance © RSNA, 2023 Online supplemental material is available for this article. See also commentary by Eberhardt in this issue.

    View details for DOI 10.1148/rycan.220070

    View details for PubMedID 37171269

  • Cost effectiveness of MRE vs VCTE in staging fibrosis for non-alcoholic fatty liver disease (NAFLD) patients with advanced fibrosis. Hepatology (Baltimore, Md.) Sangha, K., Chang, S., Cheung, R., Deshpande, V. 2023


    Non-alcoholic fatty liver disease (NAFLD) is a common cause of liver disease. To determine the optimal testing strategy for NAFLD patients with advanced fibrosis, several factors such as diagnostic accuracy, failure rates, costs of examinations, and potential treatment options need to be considered. The purpose of this study was to determine the cost-effectiveness of combination testing involving VCTE versus MRE as frontline imaging strategy for NAFLD patients with advanced fibrosis.A Markov model was developed from the U.S. perspective. The base-case scenario in this model included patients aged 50 years with FIB-4 score≥ 2.67 and suspected advanced fibrosis. The model included a decision tree and a Markov state-transition model including five health states: fibrosis stage 1-2, advanced fibrosis, compensated cirrhosis, decompensated cirrhosis, death. Both deterministic and probabilistic sensitivity analyses were performed.Staging fibrosis with MRE cost $8388 more than VCTE but led to an additional 1.19 QALYs with the incremental cost-effectiveness ratio (ICER) of $7048/QALY. The cost-effectiveness analysis of the 5 strategies revealed that MRE+biopsy and VCTE+MRE+biopsy were the most cost-effective with the ICERs of $8054/QALY and $8241/QALY respectively. Further, sensitivity analyses indicated that MRE remained cost-effective with a sensitivity≥0.77, while VCTE became cost-effective with a sensitivity≥0.82.MRE was not only cost effective than VCTE as the frontline modality for staging NAFLD patients with FIB-4≥2.67 with ICER of $7048/QALY but also remained cost effective when used as a follow-up in instances of VCTE failure to diagnose.

    View details for DOI 10.1097/HEP.0000000000000262

    View details for PubMedID 37018145

  • T1 signal intensity ratio of the pancreas as an imaging biomarker for the staging of chronic pancreatitis. Abdominal radiology (New York) Tirkes, T., Dasyam, A. K., Shah, Z. K., Fogel, E. L., Vege, S. S., Li, L., Li, S., Chang, S. T., Farinas, C. A., Grajo, J. R., Mawad, K., Takahashi, N., Venkatesh, S. K., Wachsman, A., Fisher, W. E., Forsmark, C. E., Hart, P. A., Pandol, S. J., Park, W. G., Van Den Eeden, S. K., Yang, Y., Topazian, M., Andersen, D. K., Serrano, J., Conwell, D. L., Yadav, D., Consortium for the Study of Chronic Pancreatitis, D. 2022


    PURPOSE: Our purpose was to validate the T1 SIR (T1 score) as an imaging biomarker for the staging of CP in a large, multi-institutional, prospective study.METHODS: The prospective study population included 820 participants enrolled in the PROCEED study from nine clinical centers between June 2017 and December 2021. A radiologist at each institution used a standardized method to measure the T1 signal intensity of the pancreas and the reference organs (spleen, paraspinal muscle, liver), which was used to derive respective T1 scores. Participants were stratified according to the seven mechanistic stages of chronic pancreatitis (MSCP 0-6) based on their clinical history, MRCP, and CT findings.RESULTS: The mean pancreas-to-spleen T1 score was 1.30 in participants with chronic abdominal pain, 1.22 in those with acute or recurrent acute pancreatitis, and 1.03 in definite CP. After adjusting for covariates, we observed a linear, progressive decline in the pancreas-to-spleen T1 score with increasing MSCP from 0 to 6. The mean pancreas-to-spleen T1 scores were 1.34 (MSCP 0), 1.27 (MSCP 1), 1.21 (MSCP 2), 1.16 (MSCP 3), 1.18 (MSCP 4), 1.12 (MSCP 5), and 1.05 (MSCP 6) (p<0.0001). The pancreas-to-liver and pancreas-to-muscle T1 scores showed less linear trends and wider confidence intervals.CONCLUSION: The T1 score calculated by SIR of the pancreas-to-spleen shows a negative linear correlation with the progression of chronic pancreatitis. It holds promise as a practical imaging biomarker in evaluating disease severity in clinical research and practice.

    View details for DOI 10.1007/s00261-022-03611-4

    View details for PubMedID 35857066

  • Inter-observer variability of radiologists for Cambridge classification of chronic pancreatitis using CT and MRCP: results from a large multi-center study. Abdominal radiology (New York) Tirkes, T., Shah, Z. K., Takahashi, N., Grajo, J. R., Chang, S. T., Wachsman, A. M., Mawad, K., Farinas, C. A., Li, L., Appana, S. N., Conwell, D. L., Yadav, D., Dasyam, A. K., Consortium for the Study of Chronic Pancreatitis, D. 2020


    PURPOSE: Determine inter-observer variability among radiologists in assigning Cambridge Classification (CC) of chronic pancreatitis (CP) based on magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) and contrast-enhanced CT (CECT).METHODS: Among 422 eligible subjects enrolled into the PROCEED study between 6/2017 and 8/2018, 39 were selected randomly for this study (chronic abdominal pain (n=8; CC of 0), suspected CP (n=22; CC of 0, 1 or 2) or definite CP (n=9; CC of 3 or 4). Each imaging was scored by the local radiologist (LRs) and three of five central radiologists (CRs) at other consortium sites. The CRs were blinded to clinical data and site information of the participants. We compared the CC score assigned by the LR with the consensus CC score assigned by the CRs. The weighted kappa statistic (K) was used to estimate the inter-observer agreement.RESULTS: For the majority of subjects (34/39), the group assignment by LR agreed with the consensus composite CT/MRCP score by the CRs (concordance ranging from 75 to 89% depending on cohort group). There was moderate agreement (63% and 67% agreed, respectively) between CRs and LRs in both the CT score (weighted Kappa [95% CI]=0.56 [0.34, 0.78]; p-value=0.57) and the MR score (weighted Kappa [95% CI]=0.68 [0.49, 0.86]; p-value=0.72). The composite CT/MR score showed moderate agreement (weighted Kappa [95% CI]=0.62 [0.43, 0.81]; p-value=0.80).CONCLUSION: There is a high degree of concordance among radiologists for assignment of CC using MRI and CT.

    View details for DOI 10.1007/s00261-020-02521-7

    View details for PubMedID 32285180

  • View-Sharing Artifact Reduction With Retrospective Compressed Sensing Reconstruction in the Context of Contrast-Enhanced Liver MRI for Hepatocellular Carcinoma (HCC) Screening. Journal of magnetic resonance imaging : JMRI Shaikh, J., Stoddard, P. B., Levine, E. G., Roh, A. T., Saranathan, M., Chang, S. T., Muelly, M. C., Hargreaves, B. A., Vasanawala, S. S., Loening, A. M. 2018


    BACKGROUND: View-sharing (VS) increases spatiotemporal resolution in dynamic contrast-enhanced (DCE) MRI by sharing high-frequency k-space data across temporal phases. This temporal sharing results in respiratory motion within any phase to propagate artifacts across all shared phases. Compressed sensing (CS) eliminates the need for VS by recovering missing k-space data from pseudorandom undersampling, reducing temporal blurring while maintaining spatial resolution.PURPOSE: To evaluate a CS reconstruction algorithm on undersampled DCE-MRI data for image quality and hepatocellular carcinoma (HCC) detection.STUDY TYPE: Retrospective.SUBJECTS: Fifty consecutive patients undergoing MRI for HCC screening (29 males, 21 females, 52-72 years).FIELD STRENGTH/SEQUENCE: 3.0T MRI. Multiphase 3D-SPGR T1 -weighted sequence undersampled in arterial phases with a complementary Poisson disc sampling pattern reconstructed with VS and CS algorithms.ASSESSMENT: VS and CS reconstructions evaluated by blinded assessments of image quality and anatomic delineation on Likert scales (1-4 and 1-5, respectively), and HCC detection by OPTN/UNOS criteria including a diagnostic confidence score (1-5). Blinded side-by-side reconstruction comparisons for lesion depiction and overall series preference (-3-3).STATISTICAL ANALYSIS: Two-tailed Wilcoxon signed rank tests for paired nonparametric analyses with Bonferroni-Holm multiple-comparison corrections. McNemar's test for differences in lesion detection frequency and transplantation eligibility.RESULTS: CS compared with VS demonstrated significantly improved contrast (mean 3.6 vs. 2.9, P<0.0001) and less motion artifact (mean 3.6 vs. 3.2, P=0.006). CS compared with VS demonstrated significantly improved delineations of liver margin (mean 4.5 vs. 3.8, P=0.0002), portal veins (mean 4.5 vs. 3.7, P<0.0001), and hepatic veins (mean 4.6 vs. 3.5, P<0.0001), but significantly decreased delineation of hepatic arteries (mean 3.2 vs. 3.7, P=0.004). No significant differences were seen in the other assessments.DATA CONCLUSION: Applying a CS reconstruction to data acquired for a VS reconstruction significantly reduces motion artifacts in a clinical DCE protocol for HCC screening.LEVEL OF EVIDENCE: 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

    View details for PubMedID 30390358

  • Variable-Density Single-Shot Fast Spin-Echo MRI with Deep Learning Reconstruction by Using Variational Networks RADIOLOGY Chen, F., Taviani, V., Malkiel, I., Cheng, J. Y., Tamir, J. I., Shaikh, J., Chang, S. T., Hardy, C. J., Pauly, J. M., Vasanawala, S. S. 2018; 289 (2): 366–73
  • Reporting Standards for Chronic Pancreatitis by Using CT, MRI, and MR Cholangiopancreatography: The Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer. Radiology Tirkes, T., Shah, Z. K., Takahashi, N., Grajo, J. R., Chang, S. T., Venkatesh, S. K., Conwell, D. L., Fogel, E. L., Park, W., Topazian, M., Yadav, D., Dasyam, A. K., Consortium for the Study of Chronic Pancreatitis, D. 2018: 181353


    Chronic pancreatitis is an inflammatory condition of the pancreas with clinical manifestations ranging from abdominal pain, acute pancreatitis, exocrine and/or endocrine dysfunction, and pancreatic cancer. There is a need for longitudinal studies in well-phenotyped patients to ascertain the utility of cross-sectional imaging findings of chronic pancreatitis for diagnosis and assessment of disease severity. CT and MR cholangiopancreatography are the most common cross-sectional imaging studies performed for the evaluation of chronic pancreatitis. Currently, there are no universal reporting standards for chronic pancreatitis. Several features of chronic pancreatitis are applied clinically, such as calcifications, parenchymal T1 signal changes, focal or diffuse gland atrophy, or irregular contour of the gland. Such findings have not been incorporated into standardized diagnostic criteria. There is also lack of consensus on quantification of disease severity in chronic pancreatitis, other than by using ductal features alone as described in the Cambridge classification. The Consortium for the Study of Chronic Pancreatitis, Diabetes, and Pancreatic Cancer (CPDPC) was established by the National Institute of Diabetes and Digestive and Kidney Diseases and the National Cancer Institute in 2015 to undertake collaborative studies on chronic pancreatitis, diabetes mellitus, and pancreatic adenocarcinoma. CPDPC investigators from the Adult Chronic Pancreatitis Working Group were tasked with development of a new consensus approach to reporting features of chronic pancreatitis aimed to standardize diagnosis and assessment of disease severity for clinical trials. This consensus statement presents and defines features of chronic pancreatitis along with recommended reporting metrics. © RSNA, 2018 Online supplemental material is available for this article. See also the editorial by Megibow in this issue.

    View details for PubMedID 30325281

  • Variable-Density Single-Shot Fast Spin-Echo MRI with Deep Learning Reconstruction by Using Variational Networks. Radiology Chen, F., Taviani, V., Malkiel, I., Cheng, J. Y., Tamir, J. I., Shaikh, J., Chang, S. T., Hardy, C. J., Pauly, J. M., Vasanawala, S. S. 2018: 180445


    Purpose To develop a deep learning reconstruction approach to improve the reconstruction speed and quality of highly undersampled variable-density single-shot fast spin-echo imaging by using a variational network (VN), and to clinically evaluate the feasibility of this approach. Materials and Methods Imaging was performed with a 3.0-T imager with a coronal variable-density single-shot fast spin-echo sequence at 3.25 times acceleration in 157 patients referred for abdominal imaging (mean age, 11 years; range, 1-34 years; 72 males [mean age, 10 years; range, 1-26 years] and 85 females [mean age, 12 years; range, 1-34 years]) between March 2016 and April 2017. A VN was trained based on the parallel imaging and compressed sensing (PICS) reconstruction of 130 patients. The remaining 27 patients were used for evaluation. Image quality was evaluated in an independent blinded fashion by three radiologists in terms of overall image quality, perceived signal-to-noise ratio, image contrast, sharpness, and residual artifacts with scores ranging from 1 (nondiagnostic) to 5 (excellent). Wilcoxon tests were performed to test the hypothesis that there was no significant difference between VN and PICS. Results VN achieved improved perceived signal-to-noise ratio (P = .01) and improved sharpness (P < .001), with no difference in image contrast (P = .24) and residual artifacts (P = .07). In terms of overall image quality, VN performed better than did PICS (P = .02). Average reconstruction time ± standard deviation was 5.60 seconds ± 1.30 per section for PICS and 0.19 second ± 0.04 per section for VN. Conclusion Compared with the conventional parallel imaging and compressed sensing reconstruction (PICS), the variational network (VN) approach accelerates the reconstruction of variable-density single-shot fast spin-echo sequences and achieves improved overall image quality with higher perceived signal-to-noise ratio and sharpness.

    View details for PubMedID 30040039

  • Molecular and Clinical Approach to Intra-abdominal Adverse Effects of Targeted Cancer Therapies RADIOGRAPHICS Chang, S. T., Menias, C. O., Lubner, M. G., Mellnick, V. M., Hara, A. K., Desser, T. S. 2017; 37 (5): 1461–82


    Targeted cancer therapies encompass an exponentially growing number of agents that involve a myriad of molecular pathways. To excel within this rapidly changing field of clinical oncology, radiologists must eschew traditional organ system-based approaches of cataloging adverse effects in favor of a conceptual framework that incorporates molecular mechanisms and associated clinical outcomes. Understanding molecular mechanisms that underlie imaging manifestations of adverse effects and known associations with treatment response allows radiologists to more effectively recognize adverse effects and differentiate them from tumor progression. Radiologists can therefore more effectively guide oncologists in the management of adverse effects and treatment decisions regarding continuation or cessation of drug therapy. Adverse effects from targeted cancer therapies can be classified into four categories: (a) category 1, on-target adverse effects associated with treatment response; (b) category 2, on-target adverse effects without associated treatment response; (c) category 3, off-target adverse effects; and (d) category 4, tumor necrosis-related adverse effects. This review focuses on adverse effects primarily within the abdomen and pelvis classified according to established or hypothesized molecular mechanisms and illustrated with images of classic examples and several potential emerging toxic effects. ©RSNA, 2017.

    View details for PubMedID 28753381

  • Sonographic Differentiation of Complicated From Uncomplicated Appendicitis Implications for Antibiotics-First Therapy JOURNAL OF ULTRASOUND IN MEDICINE Xu, Y., Jeffrey, R. B., Chang, S. T., DiMaio, M. A., Olcott, E. W. 2017; 36 (2): 269-277


    To evaluate sonographic findings as indicators of complicated versus uncomplicated appendicitis in the setting of known appendicitis, a necessary distinction in deciding whether to proceed with antibiotic therapy or with appendectomy.With Institutional Review Board approval and Health Insurance Portability and Accountability Act compliance, appendiceal sonograms of 119 patients with histopathologically proven appendicitis were retrospectively blindly reviewed to determine the presence or absence of the normally echogenic submucosal layer, the presence of mural hyperemia, periappendiceal fluid, appendicoliths, and hyperechoic periappendiceal fat and to determine the maximum outside diameter. Results were compared with the presence of complicated versus uncomplicated appendicitis on histopathologic examination and assessed by both univariate and mulitvariate logistic regression; confidence intervals (CIs) of proportions were assessed by the exact binomial test.Thirty-two (26.9%) of the 119 patients had complicated appendicitis, including 11 with gangrenous appendicitis without perforation and 21 with gangrenous appendicitis and perforation. Loss of the submucosal layer was the only independent significant indicator of complicated appendicitis in multivariate regression (P < .001) and provided sensitivity and specificity values of 100.0% (95% CI, 89.1%-100.0%) and 92.0% (95% CI, 84.1%-96.7%), respectively.Loss of the normally echogenic submucosal layer was the most useful sonographic finding for discriminating complicated from uncomplicated appendicitis, being the only finding independently and significantly associated with complicated appendicitis and, additionally, providing both high sensitivity and high specificity. This information may help a physician decide whether to proceed with antibiotic therapy or with appendectomy when treating a patient with appendicitis.

    View details for DOI 10.7863/ultra.16.03109

    View details for PubMedID 28039865

  • Preoperative Multidetector CT Diagnosis of Extrapancreatic Perineural or Duodenal Invasion Is Associated with Reduced Postoperative Survival after Pancreaticoduodenectomy for Pancreatic Adenocarcinoma: Preliminary Experience and Implications for Patient Care RADIOLOGY Chang, S. T., Jeffrey, R. B., Patel, B. N., DiMaio, M. A., Rosenberg, J., Willmann, J. K., Olcott, E. W. 2016; 281 (3): 816-825


    Purpose To test the hypothesis that patients with pancreatic adenocarcinoma who otherwise are viewed to have resectable disease but have preoperative findings of extrapancreatic perineural invasion (EPNI) and/or duodenal invasion at multidetector computed tomography (CT) have reduced postoperative survival after pancreaticoduodenectomy for pancreatic ductal adenocarcinoma (PDAC). Materials and Methods This study was approved by the institutional review board and complied with HIPAA. The authors retrospectively evaluated 76 consecutive patients with PDAC who underwent preoperative multidetector CT and subsequent pancreaticoduodenectomy. Two radiologists blinded to surgical pathology results and clinical outcome evaluated multidetector CT images for evidence of EPNI and duodenal invasion; discrepancies were resolved by consensus. Also determined for each patient were resected lymph node status, tumor size, surgical margin status, time to progression, and time to death. Data were assessed with the Goodman-Kruskal gamma for correlations among indicators and the log-rank test, Kaplan-Meier estimates, and multivariate Cox proportional hazards regression for survival analysis. Results In univariate analysis, duodenal invasion and/or EPNI on preoperativemultidetector CT images was associated with significantly decreased progression-free survival (P < .0001) and overall survival (P = .0013), and the clinical indicators (lymph node status, tumor size, and surgical margin status) as well as duodenal invasion and/or EPNI showed correlation with each other. In multivariate regression that included multidetector CT findings as well as the three traditional clinical indicators, only duodenal invasion and/or EPNI showed significant independent association with reduction in both modes of survival (P < .0001 and P = .014, respectively). Interobserver agreement was substantial with respect to EPNI and duodenal invasion (κ = 0.691 and 0.682, respectively). Conclusion Patients with evidence of EPNI and/or duodenal invasion on preoperative multidetector CT images have significantly reduced survival after pancreaticoduodenectomy for PDAC. (©) RSNA, 2016.

    View details for DOI 10.1148/radiol.2016152790

    View details for PubMedID 27438167

  • The imaging findings of typical and atypical genital and gynecologic infections ABDOMINAL RADIOLOGY Orlowski, H. L., Mellnick, V. M., Dahiya, N., Katz, D. S., Chang, S. T., Siegel, C., Menias, C. O. 2016; 41 (12): 2294-2309


    Genital and gynecologic infections are common medical problems, affecting millions of women worldwide. The spectrum of these infections extends from the labia, including processes such as necrotizing fasciitis and anogenital warts, to the upper reproductive tracts in conditions including endometritis and pelvic inflammatory disease. Although often a clinical diagnosis, the radiologist plays an important role in determining the etiology of acute abdominal and pelvic pain as well as facilitating the diagnosis for cases which are not clinically straightforward. Imaging also plays an important role in assessing the complications and sequelae of these conditions, including infertility, chronic abdominal and pelvic pain, and pelvic adhesions. Familiarity with the appearances of these infections, their complications, and their potential mimics on sonography, computed tomography, magnetic resonance imaging, and hysterosalpingography is important for timely diagnosis and optimal clinical outcomes.

    View details for DOI 10.1007/s00261-016-0749-0

    View details for Web of Science ID 000390050600002

    View details for PubMedID 27251736

  • Three-step sequential positioning algorithm during sonographic evaluation for appendicitis increases appendiceal visualization rate and reduces CT use. AJR. American journal of roentgenology Chang, S. T., Jeffrey, R. B., Olcott, E. W. 2014; 203 (5): 1006-1012


    The purpose of this article is to examine the rates of appendiceal visualization by sonography, imaging-based diagnoses of appendicitis, and CT use after appendiceal sonography, before and after the introduction of a sonographic algorithm involving sequential changes in patient positioning.We used a search engine to retrospectively identify patients who underwent graded-compression sonography for suspected appendicitis during 6-month periods before (period 1; 419 patients) and after (period 2; 486 patients) implementation of a new three-step positional sonographic algorithm. The new algorithm included initial conventional supine scanning and, as long as the appendix remained nonvisualized, left posterior oblique scanning and then "second-look" supine scanning. Abdominal CT within 7 days after sonography was recorded.Between periods 1 and 2, appendiceal visualization on sonography increased from 31.0% to 52.5% (p < 0.001), postsonography CT use decreased from 31.3% to 17.7% (p < 0.001), and the proportion of imaging-based diagnoses of appendicitis made by sonography increased from 63.8% to 85.7% (p = 0.002). The incidence of appendicitis diagnosed by imaging (either sonography or CT) remained similar at 16.5% and 17.3%, respectively (p = 0.790). Sensitivity and overall accuracy were 57.8% (95% CI, 44.8-70.1%) and 93.0% (95% CI, 90.1-95.3%), respectively, in period 1 and 76.5% (95% CI, 65.8-85.2%) and 95.4% (95% CI, 93.1-97.1%), respectively, in period 2. Similar findings were observed for adults and children.Implementation of an ultrasound algorithm with sequential positioning significantly improved the appendiceal visualization rate and the proportion of imaging-based diagnoses of appendicitis made by ultrasound, enabling a concomitant decrease in abdominal CT use in both children and adults.

    View details for DOI 10.2214/AJR.13.12334

    View details for PubMedID 25341138

  • Metastatic Melanoma in the Chest and Abdomen: The Great Radiologic Imitator SEMINARS IN ULTRASOUND CT AND MRI Chang, S. T., Desser, T. S., Gayer, G., Menias, C. O. 2014; 35 (3): 272-289


    Metastatic melanoma causes an unpredictable variety of manifestations in the chest and abdomen that may be indistinguishable from other diseases by imaging alone. Melanoma metastases commonly involve the lymph nodes, lungs, liver, and small bowel, but virtually any organ can be affected. Newer modalities, such as contrast-enhanced ultrasound and whole-body magnetic resonance imaging, may provide more sensitive detection of metastatic melanoma for diagnosis, staging, and surveillance. An understanding of the predominantly hematogenous nature of metastatic spread by melanoma as well as a high index of suspicion in any patient with a history of melanoma may allow for more precise and confident diagnosis.

    View details for DOI 10.1053/j.sult.2014.02.001

    View details for PubMedID 24929267

  • Imaging of Primary Gastrointestinal Lymphoma SEMINARS IN ULTRASOUND CT AND MRI Chang, S. T., Menias, C. O. 2013; 34 (6): 558-565


    Primary gastrointestinal (GI) lymphoma most often arises from stomach, small bowel, or colon. The 2 most common subtypes of primary GI lymphoma include low-grade mucosa-associated lymphoid tissue lymphoma, strongly associated with Helicobacter pylori infection, and high-grade diffuse, large B-cell lymphoma. Primary GI lymphoma demonstrates a myriad of imaging manifestations that can commonly mimic other pathologies. Timely and accurate diagnosis remains important because treatment and prognosis of primary GI lymphoma differ significantly from other GI malignancies and even lymphoma of other primary sites.

    View details for DOI 10.1053/j.sult.2013.05.008

    View details for Web of Science ID 000328656800007

    View details for PubMedID 24332207

  • Sonography of the normal appendix: its varied appearance and techniques to improve its visualization. Ultrasound quarterly Ung, C., Chang, S. T., Jeffrey, R. B., Patel, B. N., Olcott, E. W. 2013; 29 (4): 333-341


    The sonographic identification of the normal appendix is crucial to the success of ultrasound as an effective screening method for diagnosing acute appendicitis. The normal appendix can be challenging to identify on sonography, however, because it is a narrow tubular structure and has variable sonographic appearances. Moreover, the tip of the appendix can be quite variable in location. In this article, we review the various sonographic appearances of the normal appendix and highlight strategies to improve its visualization.

    View details for DOI 10.1097/RUQ.0b013e3182a2aa8e

    View details for PubMedID 24263759

  • Identification of a biomarker panel using a multiplex proximity ligation assay improves accuracy of pancreatic cancer diagnosis JOURNAL OF TRANSLATIONAL MEDICINE Chang, S. T., Zahn, J. M., Horecka, J., Kunz, P. L., Ford, J. M., Fisher, G. A., Le, Q. T., Chang, D. T., Ji, H., Koong, A. C. 2009; 7


    Pancreatic cancer continues to prove difficult to clinically diagnose. Multiple simultaneous measurements of plasma biomarkers can increase sensitivity and selectivity of diagnosis. Proximity ligation assay (PLA) is a highly sensitive technique for multiplex detection of biomarkers in plasma with little or no interfering background signal.We examined the plasma levels of 21 biomarkers in a clinically defined cohort of 52 locally advanced (Stage II/III) pancreatic ductal adenocarcinoma cases and 43 age-matched controls using a multiplex proximity ligation assay. The optimal biomarker panel for diagnosis was computed using a combination of the PAM algorithm and logistic regression modeling. Biomarkers that were significantly prognostic for survival in combination were determined using univariate and multivariate Cox survival models.Three markers, CA19-9, OPN and CHI3L1, measured in multiplex were found to have superior sensitivity for pancreatic cancer vs. CA19-9 alone (93% vs. 80%). In addition, we identified two markers, CEA and CA125, that when measured simultaneously have prognostic significance for survival for this clinical stage of pancreatic cancer (p < 0.003).A multiplex panel assaying CA19-9, OPN and CHI3L1 in plasma improves accuracy of pancreatic cancer diagnosis. A panel assaying CEA and CA125 in plasma can predict survival for this clinical cohort of pancreatic cancer patients.

    View details for DOI 10.1186/1479-5876-7-105

    View details for PubMedID 20003342

  • Gemcitabine chemotherapy and single-fraction stereotactic body radiotherapy for locally advanced pancreatic cancer INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS Schellenberg, D., Goodman, K. A., Lee, F., Chang, S., Kuo, T., Ford, J. M., Fisher, G. A., Quon, A., Desser, T. S., Norton, J., Greco, R., Yang, G. P., Koong, A. C. 2008; 72 (3): 678-686


    Fractionated radiotherapy and chemotherapy for locally advanced pancreatic cancer achieves only modest local control. This prospective trial evaluated the efficacy of a single fraction of 25 Gy stereotactic body radiotherapy (SBRT) delivered between Cycle 1 and 2 of gemcitabine chemotherapy.A total of 16 patients with locally advanced, nonmetastatic, pancreatic adenocarcinoma received gemcitabine with SBRT delivered 2 weeks after completion of the first cycle. Gemcitabine was resumed 2 weeks after SBRT and was continued until progression or dose-limiting toxicity. The gross tumor volume, with a 2-3-mm margin, was treated in a single 25-Gy fraction by Cyberknife. Patients were evaluated at 4-6 weeks, 10-12 weeks, and every 3 months after SBRT.All 16 patients completed SBRT. A median of four cycles (range one to nine) of chemotherapy was delivered. Three patients (19%) developed local disease progression at 14, 16, and 21 months after SBRT. The median survival was 11.4 months, with 50% of patients alive at 1 year. Patients with normal carbohydrate antigen (CA)19-9 levels either at diagnosis or after Cyberknife SBRT had longer survival (p <0.01). Acute gastrointestinal toxicity was mild, with 2 cases of Grade 2 (13%) and 1 of Grade 3 (6%) toxicity. Late gastrointestinal toxicity was more common, with five ulcers (Grade 2), one duodenal stenosis (Grade 3), and one duodenal perforation (Grade 4). A trend toward increased duodenal volumes radiated was observed in those experiencing late effects (p = 0.13).SBRT with gemcitabine resulted in comparable survival to conventional chemoradiotherapy and good local control. However, the rate of duodenal ulcer development was significant.

    View details for DOI 10.1016/j.ijrobp.2008.01.051

    View details for PubMedID 18395362

  • Impact of integrated PET/CT on variability of target volume delineation in rectal cancer TECHNOLOGY IN CANCER RESEARCH & TREATMENT Patel, D. A., Chang, S. T., Goodman, K. A., Quon, A., Thorndyke, B., Gambhir, S. S., McMillan, A., Loo, B. W., Koong, A. C. 2007; 6 (1): 31-36


    Several studies have demonstrated substantial variability among individual radiation oncologists in defining target volumes using computed tomography (CT). The objective of this study was to determine the impact of combined positron emission tomography and computed tomography (PET/CT) on inter-observer variability of target volume delineation in rectal cancer. We also compared the relative concordance of two PET imaging tracers, 18F-fluorodeoxyglucose (FDG) and 18F-fluorodeoxythymidine (FLT), against conventional computed tomography (CT). Six consecutive patients with locally advanced rectal cancer were enrolled onto an institutional protocol involving preoperative chemoradiotherapy and correlative studies including FDG- and FLT-PET scans acquired in the treatment position. Using these image data sets, four radiation oncologists independently delineated primary and nodal gross tumor volumes (GTVp and GTVn) for a hypothetical boost treatment. Contours were first defined based on CT alone with observers blinded to the PET images, then based on combined PET/CT. An inter-observer similarity index (SI), ranging from a value of 0 for complete disagreement to 1 for complete agreement of contoured voxels, was calculated for each set of volumes. For primary gross tumor volume (GTVp), the difference in estimated SI between CT and FDG was modest (CT SI = 0.77 vs. FDG SI = 0.81), but statistically significant (p = 0.013). The SI difference between CT and FLT for GTVp was also slight (FLT SI = 0.80) and marginally non-significant (p < 0.082). For nodal gross tumor volume, (GTVn), SI was significantly lower for CT based volumes with an estimated SI of 0.22 compared to an estimated SI of 0.70 for FDG-PET/CT (p < 0.0001) and an estimated SI of 0.70 for FLT-PET/CT (p < 0.0001). Boost target volumes in rectal cancer based on combined PET/CT results in lower inter-observer variability compared with CT alone, particularly for nodal disease. The use of FDG and FLT did not appear to be different from this perspective.

    View details for Web of Science ID 000244732600005

    View details for PubMedID 17241098

  • Stereotactic body radiotherapy for unresectable pancreatic cancer 38th San Francisco Radiation Oncology Conference Chang, S. T., Goodman, K. A., Yang, G. R., Koong, A. C. KARGER. 2007: 386–394


    Pancreatic cancer is a devastating disease with few effective treatment modalities. Recent technological advances have made possible the delivery of single-fraction stereotactic body radiotherapy (SBRT) to patients with locally advanced pancreatic tumors. This paper presents experience at Stanford University with SBRT for patients with unresectable pancreatic cancer. Pancreatic tumors of up to 100 cm3 could be treated. Patients achieved greater than 90% local control for the remainder of their lives. Currently, the standard dose for pancreatic tumors treated at this institution is 25 Gy given in a single fraction. Four-dimensional CT and PET scans have been essential for optimal treatment planning. PET-CT scanning may be a more effective method for evaluating tumor response than conventional CT scanning. Adjuvant systemic therapies could be administered in coordination with SBRT. SBRT is an effective method of treating patients resulting in excellent local control. Current research is aimed at defining the optimal method of combining this treatment with other cancer therapies.

    View details for Web of Science ID 000248596600023

    View details for PubMedID 17641521