Abstract
Colorectal cancer commonly shows strong focal FDG uptake. The files of 3,754 examinations of FDG-PET/CT without known active lesions of colorectal cancer were retrospectively reviewed. Unexpected colonic focal uptake was found in 65 patients (1.73%). Focal uptake was frequently observed in ascending colon, sigmoid colon, and rectum. Further examination was performed in 53 patients (81.5%) mainly by total colonoscopy. There were 20 cancers, 16 adenomas, 12 with no lesions, and 5 other benign processes. The cancer detection rate was 0.53%. The positive predictive value (PPV) of cancer was 30.8%, and PPV of neoplasm was 55.4%. The high rate of neoplasm in focal uptake justifies total colonoscopy as the next step. Colorectal cancer detection should be one of the main targets of FDG-PET/CT diagnosis.
