The Clinical Meaning of Benign Colon Uptake in 18F-FDG PET: Comparison with Colonoscopic Findings

BACKGROUND/AIMS Benign colon (18)F-fluorodeoxyglucose (FDG) uptake is frequently observed in asymptomatic individuals. Aims of this study were to investigate the benign colon uptake by whole body FDG-positron emission tomography (PET) in asymptomatic adults and to correlate those results with colonoscopic and histologic findings. METHODS Among 3,540 subjects who had undergone FDG-PET, 43 subjects who were diagnosed to have benign colon uptake in FDG-PET and underwent colonoscopy were retrospectively reviewed. Subjects were classified as diffuse or focal groups based on their FDG uptake patterns. PET results were analyzed together with colonoscopic and histologic findings. RESULTS Forty-three subjects showed benign colon uptake in FDG-PET; 28 of them were shown as the diffuse group, while other 15 subjects were classified as the focal group. Five subjects among those showed diffuse uptake were diagnosed as adenoma. Seven among 15 subjects who showed focal uptake were diagnosed as adenocarcinoma (n=2), adenoma (n=3), or non-neoplastic polyp (n=2). Positive predictive values were 25% in the diffuse group and 47% in the focal group. CONCLUSIONS We recommend that patients showing benign FDG uptake in the colon should be further evaluated by colonoscopy, especially for patients with focal FDG uptake.