PET/CT evaluation of the physiologic accumulation of 18F-FDG within the gallbladder vesicle.

The aim of this study was to investigate physiological fluorine 18-labeled fluourodeoxyglucose accumulation in the gallbladder (GB) during clinical positron emission tomography (PET) examinations. Three patient groups were included. In Group 1, nine patients with higher fluourodeoxyglucose (FDG) accumulation in the GB than in the liver were examined, followed up and finally diagnosed. In Group 2, the correlations between FDG GB accumulation and various parameters in 286 patients were investigated. In Group 3, changes in FDG GB accumulation between early and delayed PET scans were analyzed in 12 patients. In Group 1, all nine patients who exhibited a high FDG GB accumulation had no evidence of GB disease. In Group 2, FDG GB accumulation was significantly correlated with the injection-scan time interval and inversely correlated with the GB size index. Group 3 showed a significant increase in FDG accumulation in the GB on delayed PET scans, compared with that seen on early scans. In clinical PET studies, FDG accumulation within the GB is infrequently observed but may be due to FDG excretion into the bile. Recognition of this phenomenon may be important to avoid misdiagnosing physiological GB FDG accumulation as indicating a pathologic status and preventing unnecessary examinations.