Clinical Significance of Incidental Colonic 18F-FDG Uptake on PET/CT Images in Patients with Gastric Adenocarcinoma

We assessed the ability of positron emission tomography-computed tomography (PET/CT) to detect synchronous colonic pathology and determined the significance of 18F-fluorodeoxyglucose (F-18-FDG) activity in the colon of gastric cancer patients. A total of 239 gastric cancer patients who underwent PET/CT and colonoscopy preoperatively were included. FDG uptake patterns on PET/CT were classified as (1) group A, focal; (2) group B, diffuse; and (3) group C, no uptake. The PET/CT findings were compared with the results of concurrent colonoscopy. In group A, a total of 123 polyps of > 0 mm were observed. Of these, nine polyps were colonic adenocarcinomas and six were high-grade dysplasia. The incidence of colonic adenocarcinomas was significantly higher in group A than in the other two groups (p = 0.037). There was a significant correlation between SUVmax values and incidence of colonic polyps of > 10 mm (r = 0.471, p = 0.04). The distribution pattern of SUVmax in polyps with adenoma (> 10 mm) was less homogenous than in polyps (> 10 mm) with adenocarcinoma. The focal colonic FDG uptake in PET/CT requires colonoscopic confirmation. The suspicion of colonic malignancy increased in the presence of polyps > 10 mm that showed a positive correlation with the SUVmax.