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CC BY-NC-ND 4.0 · World J Nucl Med 2015; 14(01): 25-30
DOI: 10.4103/1450-1147.150524
Original article

Focal Colonic FDG Activity with PET/CT: Guidelines for Recommendation of Colonoscopy

Tianye Liu
Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
,
Spencer Behr
Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
,
Sana Khan
Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
,
Robert Osterhoff
1   Department of Medicine, University of California, San Francisco, California, USA
,
Carina Aparici
Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA
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Focal 18 F-fluorodeoxyglucose (FDG) colonic activity can be incidentally seen in positron emission tomography/computed tomography (PET/CT) scans. Its clinical significance is still unclear. The purpose of this study was to assess the significance of focal FDG activity in PET/CT scans by correlating the imaging findings to colonoscopy results, and come up with some guidelines for recommendation of follow-up colonoscopy. A total of 133 patients who underwent both 18 F-FDG PET/CT for different oncological indications and colonoscopy within 3 months were retrospectively studied. Imaging, colonoscopy and pathology results were analyzed. Of the 133 FDG-PET/CT scans, 109/133 (82%) did not show focal colonic FDG activity, and 24/133 (18%) did. Of the 109/133 PET/CTs without focal colonic FDG activity, 109/109 (100%) did not have evidence of colon cancer after colonoscopy and histology. Of the 24/133 PET/CTs with focal colonic FDG activity, 10/24 (42%) had pathologic confirmation of colon cancer and 14/24 (58%) did not have evidence of colon cancer after colonoscopy and histological analysis. Sensitivity was 10/10 (100%), specificity 109/123 (89%), positive predictive value (PPV) 10/24 (42%) and negative predictive value (NPV) 109/109 (100%). Incidental focal 18 FDG activity in PET/CT imaging shows a high sensitivity, specificity and NPV for malignancy, with a not so high PPV of 42%. Although some people would argue that a 42% chance of malignancy justifies colonoscopy, this maybe is not possible in all cases. However, the high sensitivity of the test does not allow these studies to be overlooked. We provide our recommendations as per when to send patients with focal FDG colonic activity to have further characterization with colonoscopy.

Keywords

Colorectal cancer - fluorodeoxyglucose - positron emission tomography


Publication History

Article published online:
21 May 2022

© 2015. Sociedade Brasileira de Neurocirurgia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commecial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

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