Endoscopic findings in case of incidental colonic uptake in PET-CT How to improve PET-CT specificity ?

Unexpected colonic 18FDG focal uptakes (UCFU) in PET CT oc- cur in 1.3-3.3% of cases in retrospective study and are often associ- ated with significant colorectal findings in endoscopy, especially neoplastic lesions. The purpose of our prospective study was to evaluate the significance of UCFU and to assess criteria improving PET CT specificity for advanced adenoma and neoplasia. This study was conducted in a single institution from April 2012 to Sep- tember 2013. In the 2904 patients who benefit from PET CT, 52 had an UCFU and 43 were referred for colonoscopy. After endoscopy, 8 examinations showed no colonic abnormality (18.6%), 7 showed benign lesion (16.3%), 18 showed advanced adenoma (42.9%) and 10 showed carcinoma (23.3%). There were more false positives results in the proximal colon compared to distal colon. Eighteen patients had UCFU and tomodensitometric abnormalities in the same colonic area. This pathological combination was strongly associated to the diagnosis of malignancy.