Evaluation of Lesions with Increased Fluorine-18 Fluorodeoxyglucose Uptake in the Stomach and Colon Incidental Detected by Positron Emission Tomography/Computed Tomography

Objective: One of the most common incidental increased uptake areas with fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) is the gastrointestinal tract. In this study, we retrospectively evaluated patients with gastric and colonic incidental increased 18F-FDG uptake on PET/CT.

Methods: Patients who underwent 18F-FDG PET/CT imaging and had incidental increased gastric and colonic uptake between June 2017 and June 2020 were evaluated.

Results: Of the 10,551 evaluated patients, 306 (2.9%) had colonic and 195 (1.8%) had gastric incidental 18F-FDG uptake on PET/CT. Within 120 days after imaging, 173 patients (56%) with increased colonic uptake (250 different uptake area) and 95 patients with increased gastric uptake (48.7%) who underwent endoscopic evaluation in our center were included in the study. Increased focal uptake pattern was seen in 86.4% of colonic uptake areas and 67.4% of gastric uptake areas. Malignant/premalignant diseases were identified in 80% of cases with colonic uptake, and in 21% of patients with gastric uptake areas. While maximum standardized uptake value (SUVmax) >5.9 in the colon differentiates inflammatory and malignant/premalignant diseases from benign diseases with 80% sensitivity and 97% specificity, SUVmax >5.0 in the stomach differentiates malignant/premalignant lesions from inflammatory benign diseases with 75% sensitivity and 72% specificity.

Conclusion: Focal incidental increased 18F-FDG uptake especially in the colon is associated with malignant/premalignant events, however, focal gastric uptake is not effective in differentiating malignant/premalignant lesions from benign lesions. Studies are needed for effective SUVmax values distinguish benign and malignant gastric lesions.