UNLABELLED: The aim of the project was to study hepatic bile entry into and the transit pattern within the gallbladder lumen during fasting and to introduce a new quantitative scintigraphic test for measurement of its concentration function. METHODS: Each of 10 control subjects and 10 chronic acalculous cholecystitis (CAC) patients received 111-185 MBq 99mTc-mebrofenin as a hepatic bile marker. Gamma-camera image data were collected in the anterior view on a 128 x 128 x 16 computer matrix at 1 frame per minute for 60 min for the hepatic phase and 30 min for the gallbladder phase. The radiolabeled hepatic bile area within the gallbladder lumen was traced, and the net transit area and transit time were noted. The hepatic bile transit rate was calculated (as mm2/min) and normalized to 1,000 mm2 of the anterior gallbladder area. The cholecystokinin-8-induced ejection fraction was calculated nongeometrically using counts. RESULTS: Hepatic bile entered the gallbladder continuously during fasting with a mean +/- SD of 71% +/- 20% in control subjects and 59% +/- 27% in CAC patients, which were not significantly different (P > 0.05). The maximum frontal gallbladder area was 1,699 mm2 in control subjects and 1,610 mm2 in CAC patients (P > 0.05). Radiolabeled hepatic bile entered the gallbladder first along its central long axis in both groups, at a mean of 15 min and 16 min, respectively, and traveled toward the periphery in a lamellar fashion at a normalized mean rate of 38 mm2/min and 40 mm2/min in control subjects and CAC patients, respectively. The mean ejection fraction of 17% in CAC patients was significantly lower than the mean value of 56% in control patients (P < 0.00001). CONCLUSION: Hepatic bile enters the gallbladder continuously during fasting. In patients with CAC, the gallbladder maintains the normal concentration function but the contraction and emptying are reduced significantly. This new cholescintigraphic technique enables measurement of both functions sequentially with a single dose of 99mTc-mebrofenin.