Significance of ¹⁸F-2-deoxy-2-fluoro-glucose accumulation in the stomach on positron emission tomography

To explain the accumulation of ¹⁸F-2-deoxy-2-fluoro-glucose (¹⁸FDG) on positron emission tomography (PET) in the stomach and differences in its pattern, we focus on the accumulation pattern in association with endoscopic findings of the gastric mucosa and Helicobacter pylori (Hp) infection.

Of 599 cases undergoing ¹⁸FDG-PET examinations, we retrospectively analyzed the pattern of ¹⁸FDG accumulation in the stomach, findings of upper gastrointestinal endoscopy, and Hp infection. The pattern of ¹⁸FDG accumulation was classified into three groups: localized accumulation only in the fornix (Group A, 32 patients), diffuse accumulation throughout the entire stomach (Group B, 49 patients), and no accumulation (Group C, 191 patients).

Regarding the relation between Hp infection and ¹⁸FDG accumulation, Hp infection was positive in 56.3% of Group A, 73.5% of Group B, and 24.1% of Group C, with significant differences (p < 0.001). Regarding the relation between ¹⁸FDG accumulation and gastric mucosal inflammation, when Groups A and B were compared with Group C, nearly half of the cases in the former groups had papular redness with a significantly higher frequency of redness and erosion. Three cases found to have malignant tumor were limited to the former groups. One MALT lymphoma case was also found in the same group. Accumulation of ¹⁸FDG largely corresponded to mucosal inflammation including superficial gastritis and erosive gastritis, and therefore the main cause of non-specific ¹⁸FDG accumulation was considered to be inflammatory mucosa (mainly redness). The accumulation pattern was not associated with atrophic changes of the gastric mucosa or with Hp infection, but with mucosal inflammatory changes, including redness and erosion localized to the fornix.

Accumulation of ¹⁸FDG in the stomach suggests a high probability of the presence of inflammatory change in the gastric mucosa forming a background for the development of cancer or malignant lymphoma, and thus requires further endoscopic examinations.