Ability of integrated positron emission and computed tomography to detect significant colonic pathology

BACKGROUND: The ability of integrated positron emission tomography and computed axial tomography (PET-CT) to detect colonic pathology is not fully defined. The purpose of this study was to assess the ability of PET-CT to detect colonic pathology and to determine the significance of ((18)F)2-fluoro-2-deoxyglucose ((18)F-FDG) activity noted incidentally in the colon on PET-CT. METHODS: Records for all patients who underwent PET-CT and colonoscopy at our institution were reviewed. Patients with history of colonic malignancy or colon surgery were excluded. RESULTS: Fifty-eight patients had incidental colonic (18)F-FDG activity on PET (Group A) and 272 had none (Group B). In Group A, 65% of patients had pathologic findings detected on colonoscopy that corresponded to the site of PET activity. Standardized uptake value (SUV) readings were not helpful in distinguishing true-positives from false-positives. In Group B, 11.8% of patients were found to have significant colonic findings. Lesions not detected by PET-CT included 4 colon cancers, 7 advanced adenomas, and 10 patients with colonic lymphoma. Overall, the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET-CT for detecting significant pathology were 53%, 93%, 65%, 89%, and 85%, respectively. For detecting colon cancer and adenomas 10 mm or more, the sensitivity, specificity, PPV, NPV, and accuracy of PET-CT were 72%, 90%, 45%, 96%, and 88%, respectively. CONCLUSIONS: Incidental colonic activity detected by PET-CT warrants further evaluation with colonoscopy. However, negative PET-CT does not rule out significant colonic pathology including colon cancer, advanced adenomas, or lymphoma.