Gallbladder emptying in normal volunteers. Comparative study between cholescintigraphy and ultrasonography.
To assess the reproducibility of and compare the patterns of gallbladder emptying after a fatty meal stimulus, the authors analyzed 10 healthy fasting volunteers (8 men; mean age, 32 years). Cholescintigraphy was obtained after intravenous injection of 185 MBq of Tc-99m DISIDA. A standardized fatty meal was provided 70 minutes after injection. The ejection fraction was measured sequentially by ultrasound and cholescintigraphy 15, 30, 45, and 60 minutes after eating. All patients had repeat studies within 1-3 weeks. The two methods showed a distinct gallbladder time course of emptying after the fatty meal stimulus. Nuclear medicine showed higher values of gallbladder ejection fraction at 45 and 60 minutes after eating when compared to ultrasound (P < 0.01). The plotted curves, using the four different periods of time, also showed different behavior due mainly to distinct angular coefficients (nuclear medicine, 2.6; ultrasound, 0.9). Good reproducibility of fatty meal-induced gallbladder ejection fraction at 30, 45, and 60 minutes was also observed using both methods. Thus, ultrasound and nuclear medicine are reproducible methods of studying gallbladder dynamics. However, nuclear medicine demonstrated continued excretion of bile at 45 and 60 minutes, whereas ultrasound did not show significant volume variations in these time frames.