DYNAMIC CHOLESCINTIGRAPHY - INDUCTION AND DESCRIPTION OF GALLBLADDER EMPTYING

The main purposes of this study were to investigate the best parameter for describing gallbladder emptying and whether gallbladder bile empt ying should be induced with a bolus injection or continuous infusion o f cholecystokinin-octapeptide (CCK-8). Methods: Gallbladder emptying w as measured by dynamic cholescintigraphy. Twelve healthy subjects and six patients with gallstones were examined twice with CCK-8 infusion c holescintigraphy, 0.3 ng CCK-8 kg per min for 60 min under identical c ircumstances. Another six healthy subjects randomly received bolus inj ection (0.04 mu g/kg) and infusion of CCK-8 (0.3 ng/kg per min for 60 min), respectively, during cholescintigraphy on two separate occasions . The choice of bolus dose was based on recommendations from the CCK-8 manufacturer. The infusion dose was chosen to produce plasma CCK conc entrations similar to postprandial plasma CCK levels. Results: A param eter of gallbladder emptying, mean ejection fraction (EF), was defined as 100% minus the area under the time-activity curve normalized to 10 0% and divided by the time interval from maximum to minimum counts per minute, This parameter proved superior to the well known parameters, EF(max), and EF(30), in regard to reproducibility in healthy subjects. The slope of the regression line for the mean EF was 0.998 and the in tercept value approximately 0% (p = 0.0001). The mean coefficient of v ariation was 4%. Apart from a higher mean coefficient of variation, si milar reproducibility results were seen in the six patients, The measu rements of EF(30) in healthy subjects scattered more widely around the mean compared to the mean EF and EF(max), which indicates poorer abil ity to separate normal from abnormal gallbladder emptying. Intravenous bolus injection of CCK-8 resulted in incomplete gallbladder emptying with a mean EF value of 16% (s.d. 9%; range 7%-32%) compared to 49% (s .d. 7%; range 37%-57%) following CCK-8 infusion (p = 0.004). Abdominal discomfort was observed in all subjects after administration of the b olus injection, whereas no complaints were reported during infusion. C onclusion: Mean EF is the best parameter for describing gallbladder em ptying. Moreover, slow infusion of a physiological dose of CCK-8 is pr eferable to induce gallbladder emptying because it results in more com plete emptying and has no side effects.