The potential usefulness of 18F-FDG PET/CT for detecting colorectal carcinoma and adenoma in asymptomatic adults

Objective The aim of this study was to evaluate the potential usefulness of 18 F-FDG PET/CT for detecting colorectal carcinoma and adenoma in asymptomatic adults. Methods 614 subjects were enrolled in this retrospective study. They underwent both 18 F-FDG PET/CT and colonoscopy in the same day as part of a cancer-screening program. Small focal FDG accumulation along the colorectum on 18 F-FDG PET/CT images were compared with colonoscopy findings. Size of lesion was measured on colonoscopy and histology was determined by biopsy or polypectomy. Results In 614 18 F-FDG PET/CT images, 27 foci of FDG uptakes were observed in the colorectal area in 25 subjects. The overall sensitivity and specificity of 18 F-FDG PET/CT were 5.6 and 96.8 %, respectively, but sensitivity to detect lesions larger than or equal to 1 cm was 25.8 %. On the ROC analysis, the optimal cut-off value for differentiating premalignant and malignant lesions from other benign conditions was 5.0 (sensitivity = 50 %, specificity = 88 %, AUC = 0.643). Conclusions Colonoscopic evaluation could be recommended by presence of focal colonic FDG uptake on 18 F-FDG PET/CT, especially when SUV max is over 5.