Diffuse high FDG uptake of the stomach: Comparison between PET images and endoscopic findings

Abstract

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Objectives: The etiology of diffuse gastric FDG uptake is unknown. The purpose of the study is to collect data concerning the etiology of diffuse gastric FDG uptake by comparing PET images with endoscopic findings.

Methods: From September to December 2005, 113 subjects (68 men and 45 women), aged 52±12 years, underwent whole-body PET CT and gastrofiberscopy on the same day. In PET CT studies, 60 minutes after injection of 200 MBq of FDG, emission scanning was performed (Discovery ST, GE). In each subject, the degree of gastric FDG uptake was visually compared to the FDG uptake of the liver and categolized as low (gastric FDG uptake is lower than the liver), moderate (nealry equal to the liver), or high (higher than the liver). Endoscopies were performed just prior to PET studies. In each subject, the severity of gastritis (erosive or hemorrhagic) were evaluated by 2 endoscopists and categolized as normal, moderate, or severe. In each subject, the degree of gastric FDG uptake was compared with the severity of gastritis.

Results: The degree of FDG uptake was low in 64 subjects (57%), moderate in 31 subjects (27%), and high in 18 subjects (16%), respectively (Table). The severity of gastritis was normal in 59 subjects (52%), moderate in 44 subjects (39%), and severe in 10 subjects (9%). 15 of the 18 (83%) subjects with high FDG uptake showed mild to severe gastritis, and 6 of the 18 (33%) subjects showed severe gastritis, while 3 of the 18 (17%) subjects showed no abnormality on endoscopy. Six of the 10 subjects with severe gastritis on endoscopy showed high FDG uptake on PET images while 2 of the 10 subjects showed insignificant FDG uptake. We evaluated whether or not the high FDG uptake (n=18) could be used as an indicator of severe gastritis (n=10). The sensitivity was 60% (6/10), specificity was 88% (91/103), accuracy was 86% (97/113), PPV was 33%, and NPV was 96%. Although 7 subjects underwent biopsies just prior to PET studies, no effects were observed on the PET images. Significantly higher FDG uptake was observed in upper half of the stomach (moderate and high, 43%) compared to lower half of the stomach (18%).

Conclusions: Diffuse high FDG uptake of the stomach was observed in 16% of our subjects. 33% of subjects with high FDG uptake showed severe gastritis on endoscopy while high FDG uptake did not necessarily indicate gastric lesions.

Comparison between PET images and Endoscopic findings for 113 subjects