Should we worry about incidental gastrointestinal tract involvement in positron emission tomography-computed tomography as gastroenterologist?

Background and aim : Positron emission tomography/computed tomography(PET/CT) scans detects benign clinical conditions in addition to malignancy, and this leads to additional investigation and expenditure. The purpose of our study was to assess the endoscopic and histopathologic results of incidental 18F-FDG uptake in the GI tract. Patients and Method : We enrolled 110 patients who underwent gastroscopy/colonoscopy for incidental GI tract involvement in PET/CT. Histopathologic and endoscopic results were compared with FDG uptake level, pattern of uptake(diffuse/focal), and site of involvement. Results : In our study, 52.7% of the patients were male and the mean age was 57±11 years. Among the participants, 47.3% and 52.7% of patients had upper GI tract and colorectal involvement in PET/CT, respectively. Gastritis and colonic polyps were the most common endoscopic diagnoses that caused FDG uptake in the upper and lower GI tract, respectively. Endoscopic evaluation was normal in 23.6% of patients with pathologic FDG involvement. The rates of adenomatous polyps, malignancy, and hyperplastic polyps were 18.5%, 13.6%, and 6.8%, respectively. The mean SUVmax were higher in malignant lesions than in non-malignant lesions (14.3±8.9 vs. 9.3±5.3)(p=0.02). Diffuse or focal FDG involvement patterns on PET/CT did not help to discriminate malignancy in the GI tract. Conclusion : Malignancy was detected in only 13.6% of patients with FDG involvement in the GI tract, and the involvement pattern(diffuse/focal) and SUVmax did not differentiate malignancy. (Acta gastroenterol. belg., 2018, 81, 471-475).