About

Professor John McGahan, M.D., is associated with UC Davis Health and serves as the Program Director for the Integrated Interventional Radiology Residency. He is involved in medical student education and is a faculty member within the Department of Radiology. His role includes overseeing educational programs and supporting research initiatives in radiology, contributing to the training of future radiologists and interventional radiologists.

Research topics

• Medicine
• Internal medicine
• Radiology
• Pathology
• Chemistry
• Food science
• Endocrinology
• Biology
• Obstetrics
• Gastroenterology
• Oncology
• Gynecology

Selected publications

• New Trends in Diagnosis and Imaging Follow-Up of Renal Angiomyolipomas—Part I: Classic AMLs

  Applied Radiology · 2025-04-01

  article1st authorCorresponding
  PublisherDOI

• Development of Computed Echo Tomography—An Imaging Breakthrough Addressing the Limitations of Conventional Ultrasound: A Baseline Imaging Analysis for Traumatic Injuries

  Journal of the American College of Emergency Physicians Open · 2025-05-23

  articleOpen access

  Objectives: The diagnosis and triage of trauma in austere environments using ultrasound can be severely limited by bone and other obstructions, particularly when dealing with intracranial, spinal, thoracic, and long bone injuries. A novel form of ultrasound, computed echo tomography (CET), may provide for more complete "whole body" imaging capability, thereby significantly improving patient management. Methods: To document and assess the imaging capabilities of the recently Food and Drug Administration-cleared CET system (MAUI Imaging K3900), we conducted 3 whole-body imaging sessions using 6 normal volunteers. Sixty-five predefined views of 4 different anatomic regions were obtained at each session. Images were scored by 5 clinicians experienced in trauma/general surgery, emergency medicine, and/or interventional radiology using the American College of Emergency Physicians diagnostic image quality scoring system. Imaging scores ≥3 were deemed adequate for inclusion in a "head-to-toe" imaging protocol being developed for the US military. Results: Overall, 59 views (90.8%) were deemed adequate for clinical decision making. Eleven (16.9%) had average scores between 3 and 4; and 48 (73.8%) had average scores ≥4. Imaging the cranial vault demonstrated numerous anatomic details. Extremity imaging revealed detailed views of both the boney cortex and the medullary cavity. Abdominal imaging showed clear views of the liver, spleen, and kidneys without any rib artifacts. Conclusion: CET-based imaging eliminates bone-related artifacts thereby allowing access to critical brain and extremity imaging and removes rib shadows from thoracic and abdominal organ imaging. CET imaging deserves further investigation for field-based trauma diagnosis and general imaging in other resource-limited environments.

  PublisherOA PDFDOI

• Microwave Ablation Deserves a Place at the Table for Percutaneous Ablation of Benign Thyroid Nodules

  Radiology · 2024-10-01 · 1 citations

  editorial1st authorCorresponding
  PublisherDOI

• Predictors of Benignity for Small Endophytic Echogenic Renal Masses

  Journal of Ultrasound in Medicine · 2024-10-28 · 1 citations

  articleOpen accessCorresponding

  OBJECTIVES: To evaluate for distinguishing demographic and sonographic features of small (<3 cm) endophytic angiomyolipomas (AMLs) that differentiate them from endophytic renal cell carcinomas (RCCs). METHODS: This is a Health Insurance Portablitiy and Accountablity Act (HIPAA)-compliant retrospective review of the demographics and ultrasound features of endophytic renal AMLs compared to a group of endophytic RCCs. AMLs were confirmed by identifying macroscopic fat on computed tomography (CT) or magnetic resonance imaging (MRI), while RCCs were pathologically proven. Statistical analysis was used to compare findings in the 2 groups. RESULTS: There were a total of 66 patients with 66 AMLs, and 28 patients with 28 RCCs. Of the AMLs, 57 of 66 were in females, while 10 of the 28 RCC cases were in females (P < .0001). The mean AML long and short diameters were 11.0 × 9.3 mm and were statistically significantly smaller (P < .0001) than the diameters of the RCCs (23.4 × 22.1 mm). Likewise, the ratio of the long axis to the short axis measurement was statistically significantly different between the 2 groups (P < .0001). Of the studied sonographic features, statistically different features between AMLs and RCCs included an oval versus a round shape (P < .001), respectively, and the presence versus absence of an echogenic margin, respectively. Location of the mass, mass homogeneity, mass lobulation, and presence of cystic components were not distinguishing features using P < .01 levels. CONCLUSION: For an endophytic echogenic mass in a female patient, a small size with an oval shape and an echogenic margin is statistically more likely to be an AML than an RCC, which may be helpful with management decisions.

  PublisherOA PDFDOI

• Erratum for: A Multicenter Assessment of Interreader Reliability of LI-RADS Version 2018 for MRI and CT

  Radiology · 2023-07-01 · 1 citations

  erratumOpen access
  PublisherOA PDFDOI

• Are There Ultrasound Features to Distinguish Small (&lt;3 cm) Peripheral Renal Angiomyolipomas From Renal Cell Carcinomas?

  Journal of Ultrasound in Medicine · 2023-03-29 · 5 citations

  articleOpen accessCorresponding

  Background Small echogenic renal masses are usually angiomyolipomas (AMLs), but some renal cell carcinomas (RCCs) can be echogenic and confused with an AML. Objectives This is a study to evaluate any distinguishing demographic and sonographic features of small (&lt;3 cm) peripheral AMLs versus peripheral RCCs. Methods This is a HIPAA‐compliant retrospective review of the demographics and ultrasound features of peripheral renal AMLs compared with a group of peripheral RCCs. All AMLs had confirmation of macroscopic fat as noted on thin‐cut CT or fat‐saturation MRI sequence images. All RCCs were pathologically proven. Statistical analysis was used to compare findings in the two groups. Results There were a total of 52 patients with 56 AMLs, compared with 42 patients with 42 RCCs. There were 42 females in the AML group versus 10 females in the RCC group ( P &lt; .0001). The AML diameters (15.7 mm × 12.0 mm) were statistically significantly smaller ( P largest = .0085, P smallest &lt; .001) than the diameters of the RCCs (19.9 mm × 18.5 mm). Ultrasound features found to be statistically different between the two groups were the ratio of the largest dimension to the smallest dimension ( P &lt; .001), a lobulated versus smooth margin of the AML (26 vs 30) compared with the RCC group (3 vs 39) ( P = .0012), and an “unusual” versus a round shape ( P &lt; .001) of the AML group (45 vs 11) compared with the RCC group (9 vs 33). In the multivariable model, the patient sex, margin, and mass shape were predictive of AML, with an area under the receiver operating characteristic curve of 0.92. Conclusion For a small (&lt;3 cm) peripheral echogenic mass in a female patient, a lobulated lesion with an unusual shape is highly predictive of being an AML.

  PublisherOA PDFDOI

• A Multicenter Assessment of Interreader Reliability of LI-RADS Version 2018 for MRI and CT

  Radiology · 2023-06-01 · 21 citations

  articleOpen access

  Background Various limitations have impacted research evaluating reader agreement for Liver Imaging Reporting and Data System (LI-RADS). Purpose To assess reader agreement of LI-RADS in an international multicenter multireader setting using scrollable images. Materials and Methods This retrospective study used deidentified clinical multiphase CT and MRI and reports with at least one untreated observation from six institutions and three countries; only qualifying examinations were submitted. Examination dates were October 2017 to August 2018 at the coordinating center. One untreated observation per examination was randomly selected using observation identifiers, and its clinically assigned features were extracted from the report. The corresponding LI-RADS version 2018 category was computed as a rescored clinical read. Each examination was randomly assigned to two of 43 research readers who independently scored the observation. Agreement for an ordinal modified four-category LI-RADS scale (LR-1, definitely benign; LR-2, probably benign; LR-3, intermediate probability of malignancy; LR-4, probably hepatocellular carcinoma [HCC]; LR-5, definitely HCC; LR-M, probably malignant but not HCC specific; and LR-TIV, tumor in vein) was computed using intraclass correlation coefficients (ICCs). Agreement was also computed for dichotomized malignancy (LR-4, LR-5, LR-M, and LR-TIV), LR-5, and LR-M. Agreement was compared between research-versus-research reads and research-versus-clinical reads. Results The study population consisted of 484 patients (mean age, 62 years ± 10 [SD]; 156 women; 93 CT examinations, 391 MRI examinations). ICCs for ordinal LI-RADS, dichotomized malignancy, LR-5, and LR-M were 0.68 (95% CI: 0.61, 0.73), 0.63 (95% CI: 0.55, 0.70), 0.58 (95% CI: 0.50, 0.66), and 0.46 (95% CI: 0.31, 0.61) respectively. Research-versus-research reader agreement was higher than research-versus-clinical agreement for modified four-category LI-RADS (ICC, 0.68 vs 0.62, respectively; P = .03) and for dichotomized malignancy (ICC, 0.63 vs 0.53, respectively; P = .005), but not for LR-5 (P = .14) or LR-M (P = .94). Conclusion There was moderate agreement for LI-RADS version 2018 overall. For some comparisons, research-versus-research reader agreement was higher than research-versus-clinical reader agreement, indicating differences between the clinical and research environments that warrant further study. © RSNA, 2023 Supplemental material is available for this article. See also the editorials by Johnson and Galgano and Smith in this issue. An earlier incorrect version appeared online. This article was corrected on June 28, 2023.

  PublisherOA PDFDOI

• Lung Ultrasound: A Practical Review for Radiologists

  Applied Radiology · 2023-05-01

  reviewOpen accessSenior author
  PublisherDOI

• Issue Information

  Journal of Ultrasound in Medicine · 2022-02-12 · 1 citations

  paratextOpen access
  PublisherOA PDFDOI

• The Dose-Response Effects of Consuming High Fructose Corn Syrup-Sweetened Beverages on Hepatic Lipid Content and Insulin Sensitivity in Young Adults

  Nutrients · 2022 · 16 citations

  • Medicine
  • Internal medicine
  • Endocrinology

  = 0.0027) indices of insulin sensitivity. These dose-response effects strengthen the mechanistic evidence implicating consumption of HFCS-sweetened beverages as a contributor to the metabolic dysregulation that increases risk for nonalcoholic fatty liver disease and type 2 diabetes.

  PublisherOA PDFDOI

Frequent coauthors

• Karen L. Reuter

  119 shared

• Eugenio O. Gerscovich

  35 shared

• John R. Richards

  27 shared

• Michael T. Corwin

  University of California, Davis

  26 shared

• John M. Brock

  University of California Davis Medical Center

  20 shared

• Ramit Lamba

  University of California, Davis

  16 shared

• Arthur B. Dublin

  University of California, Davis

  14 shared

• Nancy L. Keim

  Western Human Nutrition Research Center

  14 shared

Awards & honors

• Lawrence Mack Lifetime Achievement Research Award from the S…
• Castle Connolly - America's Top Doctors for Cancer, 2015, 20…
• US News & World Report - Top Physician USA, 2011, 2012, 2013…
• GI Lifetime Achievement Award at the SAR 2017 Annual Scienti…
• Society of Abdominal Radiology Lifetime Achievement Award, 2…