STANDARDIZATION OF A TECHNIQUE FOR BRIDA CHOLESCINTIGRAPHY

Calculation of ejection fraction by cholescintigraphy is a well-establ ished technique to quantify motor function of the gallbladder. All pre vious cholescintigraphic studies of gallbladder emptying have exclusiv ely used the anterior projection for gallbladder visualization. This m ay lead to inaccuracies because attenuation of gamma rays may vary dep ending on the state of gallbladder filling and body habitus. The use o f geometric means may prevent these errors. In this study, 7 healthy v olunteers were examined after the administration of 150 MBq Tc-99(m)-b romotrimethyl-IDA (Tc-99(m)-BrIDA) without any stimulus and 9 voluntee rs ingested a mixed, fatty meal 35-40 min after BrIDA injection. Imagi ng was done using a dual-headed camera in a dynamic study of 140 one-m inute frames. A plateau of activity was reached between 70 and 90 min post-injection of BrIDA and between 55-60% of maximal counts were achi eved in the gallbladder region of interest (ROI) between 35 and 40 min . Significant emptying was seen in all nine subjects after the meal. N o significant difference in ejection fraction was seen between the ant erior projection and the geometric mean of the data from the anterior and posterior projections. The slope of the gallbladder filling curve from the anterior camera data was different from that obtained from th e geometric mean, but the correlation coefficient was not significantl y different. In conclusion, adequate counts are achieved in the gallbl adder ROI 35-40 min after BrIDA injection, when the stimulus can be ad ministered to study gallbladder emptying. There is no advantage to ima ging in the anterior and posterior projections and data obtained from the anterior projection alone are adequate for gallbladder emptying st udies.