John P. McGahan, M.D. for UC Davis Health

John P. McGahan, M.D.

Director of Ultrasound

Vice Chair of Academic Affairs

Distinguished Professor

John P. McGahan is not currently accepting new patients. For assistance finding a UC Davis doctor, please call 800-2-UCDAVIS (800-282-3284).




Interventional Radiology

Radiology - Interventional Radiology

High Risk Obstetrical Imaging




Locations and Contact

Lawrence J. Ellison Ambulatory Care Center

4860 Y St.
Sacramento, CA 95817

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Additional Numbers

Clinic Phone


Physician Referrals

800-4-UCDAVIS (800-482-3284)

Philosophy of Care

Dr. McGahan's philosophy is to consider the best treatment options for his patients to insure their best outcome for their disease or cancer. He has developed and is an innovator in a variety of newer and less invasive precision therapies for focal cancer.

Clinical Interests

Dr. McGahan is a leading interventional and diagnostic radiologist. He has pioneered the use of several innovative techniques, including the use of radiofrequency ablation to treat primary and metastatic tumors (with results comparable to traditional surgery, but with fewer risks). He also has used ablation techniques in the treatment of primary and metastatic liver and renal tumors. He has treated benign and metastatic bone tumors as well. In addition, Dr. McGahan has investigated new techniques of tissue ablation for other organs, such as the prostate and breast. He has pioneered several other interventional techniques, including the development of percutaneous cholecystostomy as well as new techniques for endoluminal drainage of pelvic abscesses. He has recently studied the efficacy of abdominal ultrasound contrast in patients who have different diseases, including the use of ultrasound contrast in patients with hepatic or splenic injuries from blunt abdominal trauma.

Dr. McGahan was appointed as the chairperson by the American College of Radiology for its national Accreditation Program of Ultrasound Practices in the United States and Canada. He serves on the editorial board of several scientific journals and has edited six textbooks, including Diagnostic Ultrasound, A Logical Approach; Diagnostic Imaging of Fetal Anomalies; and most recently, an Atlas of Ultrasound Measurements.

Research/Academic Interests

Dr. McGahan's research is devoted to new minimally invasive methods of improving patient care. Among his research has been the development of percutaneous techniques in minimal treatment of cancer using energies such as radiofrequency. He has also developed techniques for percutaneous insertion of catheters into the gallbladder for acute cholecystitis. He has patented a device for ultrasound guidance of treatment of pelvic abscesses.


Abdominal Imaging

Center/Program Affiliation

UC Davis Comprehensive Cancer Center

Undergraduate School

B.S., Gonzaga University, Spokane WA 1970

Medical School

M.D., Oregon Health & Science University School of Medicine, Portland OR 1974


Rotating Internship, UC Davis Medical Center, Sacramento CA 1974-1975


Orthopedic Surgery, UC Davis Medical Center, Sacramento CA 1975-1976


Diagnostic Radiology, UC Davis Medical Center, Sacramento CA 1976-1979

Lawrence Mack Lifetime Achievement Research Award from the Society of Radiologists in Ultrasound, 2020

Castle Connolly - America's Top Doctors for Cancer, 2015, 2016, 2017, 2018, 2019

US News & World Report - Top Physician USA, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019

GI Lifetime Achievement Award at the SAR 2017 Annual Scientific Meeting and Educational Course in Hollywood, FL, 2017

Society of Abdominal Radiology Lifetime Achievement Award, 2016

Distinguished Professor - UC Davis Medical Center, 2013

Kipper B, McGahan JP, Loehfelm TW, Fananapazir G. Is Ultrasound-Guided Core Biopsy as Safe as Fine-Needle Aspiration, and Does It Add Significantly to the Diagnosis of Suspected Peritoneal Malignancy? J Ultrasound Med. 2020 Feb;39(2):239-245. doi:10.1002/jum.15095. Epub 2019 Jul 22. PMID:31329309.

Grewal A, Khera SS, McGahan JP, Wilson M, Loehfelm TW, Dall'Era MA, Evans CP. Utility of Intraprocedural Contrast-Enhanced CT in Ablation of Renal Masses. AJR Am J Roentgenol. 2020 Jan;214(1):122-128. doi:10.2214/AJR.19.21584. Epub 2019 Sep 18. PMID:31532258.

Kim NY, Lubner MG, Nystrom JT, Swietlik JF, Abel EJ, Havighurst TC, Silverman SG, McGahan JP, Pickhardt PJ. Utility of CT Texture Analysis in Differentiating Low-Attenuation Renal Cell Carcinoma From Cysts: A Bi-Institutional Retrospective Study. AJR Am J Roentgenol. 2019 Dec;213(6):1259-1266. doi:10.2214/AJR.19.21182. Epub 2019 Aug 6. PMID:31386573.

Elsayes KM, Kielar AZ, Elmohr MM, et al. White paper of the Society of Abdominal Radiology hepatocellular carcinoma diagnosis disease-focused panel on LI-RADS v2018 for CT and MRI. Abdom Radiol (NY). 2018 Oct;43(10):2625-2642. doi:10.1007/s00261-018-1744-4. PMID:30155697.

McGahan JP, Sidhar K, Fananapazir G, Early H, Corwin MT, Silverman SG, Seibert A. Renal cell carcinoma attenuation values on unenhanced CT: importance of multiple, small region-of-interest measurements. Abdom Radiol (NY). 2017 Sep;42(9):2325-2333. doi: 10.1007/s00261-017-1131-6. PMID:28389785.

Richards JR, McGahan JP. Focused Assessment with Sonography in Trauma (FAST) in 2017: What Radiologists Can Learn. Radiology. 2017 Apr;283(1):30-48. doi:10.1148/radiol.2017160107. PMID:28318439.

Early HM, McGahan JP, Scoutt LM, Revzin M, Lamba R, Corwin M, Fananapazir G, Sekhon S. Pitfalls of Sonographic Imaging of Uterine Leiomyoma. Ultrasound Q. 2016 Jun;32(2):164-74. doi:10.1097/RUQ.0000000000000176. PMID:27233072.

Sidhar K, McGahan JP, Early HM, Corwin M, Fananapazir G, Gerscovich EO. Renal Cell Carcinomas: Sonographic Appearance Depending on Size and Histologic Type. J Ultrasound Med. 2016 Feb;35(2):311-20. doi:10.7863/ultra.15.03051. Epub 2016 Jan 6. PMID:26740493.

McGahan JP. Challenges in abdominal/pelvic biopsy techniques. Abdom Imaging. 2013 Oct;38(5):1043-56. doi:10.1007/s00261-013-0006-8. PMID:23748353.

McGahan JP, Bishop J, Webb J, Howell L, Torok N, Lamba R, Corwin MT. Role of FNA and Core Biopsy of Primary and Metastatic Liver Disease. Int J Hepatol. 2013;2013:174103. doi:10.1155/2013/174103. Epub 2013 Nov 21. PMID:24369506.