V. R. Bobba

Measurement of Gallbladder Emptying Sequentially Using a Single Dose of 99mTc-Labeled Hepatobiliary Agent

The gallbladder emptying response to a single large (20 ng/kg) and four equally divided sequential small (5 ng/kg each) doses of octapeptide of cholecystokinin at 20-min intervals was measured in a paired study in six normal subjects noninvasively and quantitatively by a nongeometric method using a gamma camera, computer, and 99mTc-labeled hepatobiliary agent. The gallbladder mean (+/- SD) ejection fraction after a single large dose (20 ng/kg) of octapeptide of cholecystokinin was 34 +/- 24% and after four sequential small (5 ng/kg each) doses was 42 +/- 14%, 45 +/- 28%, 37 +/- 22%, and 32 +/- 27%, respectively (p greater than 0.05). The results of this study indicate that the first part of the 5 ng/kg sequential octapeptide of cholecystokinin dose is as effective as the single 20-ng/kg dose. The gallbladder emptying requires continued presence of high levels of octapeptide of cholecystokinin in the serum closer to levels that initiate contraction and in the absence of which the gallbladder ceases to empty further despite the fact it has inherent capacity to do so. Each of four equal octapeptide of cholecystokinin doses given sequentially elicits, on the average, an equal degree of emptying response. The method has potential for application in the study of the pharmacological effects of drugs on the biliary dynamics using a single dose of 99mTc-labeled hepatobiliary radiopharmaceutical.

The gallbladder emptying response to sequential exogenous and endogenous cholecystokinin.

The gallbladder emptying response to sequential exogenous and endogenous cholecystokinin was measured by a noninvasive, nongeometric scintigraphic technique using a single dose of technetium 99m-labelled hepatobiliary agent. The mean latent period, ejection period, ejection fraction and ejection rate following 3 min infusion of 40 ng kg-1 of octapeptide of cholecystokinin were 2.8 +/- 0.7 min, 9.8 +/- 1.3 min, 34.0 +/- 9.9% and 3.5 +/- 2.0% per minute respectively. The corresponding values following 8 oz/70 kg of oral fatty meal were 15 +/- 6 min, 24.0 +/- 5 min (P less than 0.05), 55 +/- 9.1% and 2.8 +/- 0.6% per minute respectively. The total emptying for the combined stimuli was 71.4 +/- 14.0%. The wider range in latent and ejection period following fatty meal probably reflected the variations in time of the release into circulation and the duration of bioavailability of endogenous cholecystokinin. The lower rate of ejection was over compensated by longer duration of ejection resulting in higher degree of emptying following fatty meal. It is concluded that the gallbladder emptying pattern to exogenous and endogenous cholecystokinin can be studied sequentially using a single dose of technetium 99m-labelled hepatobiliary agent.

Comparison of biokinetics and biliary imaging parameters of four Tc-99m iminodiacetic acid derivatives in normal subjects.

The biokinetics (blood clearance, urinary excretion, hepatic peak time, uptake, and excretion t-½) and the imaging parameters (the time of appearance of the common bile duct, gallbladder, and duodenum) were determined in 34 normal subjects using Tc-99m diethyl (EIDA), Tc-99m dimethyl (HIDA), Tc-99m paraisopropyl (PIPIDA), and Tc-99m parabutyl (PBIDA) iminodiacetic acid derivatives. The blood and hepatic clearance of the four agents were significantly different (P < 0.05) from each other. The 24-hour urinary excretion of PBIDA was significantly lower (P < 0.05) than the urinary excretion of the other three agents. There was no difference among the four agents in the time of appearance of the gallbladder and duodenum. The time of appearance of the common bile duct was significantly delayed with PBIDA. The maximum intensity of the common bile duct usually occurred between 20 to 40 minutes with all four agents. However, gallbladder intensity continued to increase up to 3 hours. It is concluded that in the presence of normal liver function, all four Tc-99m IDA agents show definite differences in biokinetics but these differences do not have a major effect on biliary imaging parameters. If imaging alone is the primary goal, the selection of any one of the four agents will meet the clinicians need satisfactorily.

A new scintigraphic technique for cholecystokinin gallbladder dose-response study: validation in rabbits.

Abstract: An investigation was undertaken to test whether the dose‐response curve of a cholecystokinin‐like agent (ceruletide) could be established by administering it in graded doses sequentially on the same day. The results were compared to individual doses given on separate days. The gallbladder ejection fraction (EF) was calculated for each dose using the Tc‐99m‐IDA counts to represent the gallbladder bile volume. The mean ejection fraction following 1,2.5,5, and 10 ng/kg given sequentially on the same day was 10 ± 8,22 ± 12,53 ± 13, and 85 ± 3 per cent, respectively. The ejection fraction for 2.5,5, and 10 ng/kg given on separate days was 29.7, 57.14, and 93.3 per cent, respectively, and was similar to the values obtained when the identical dose was given sequentially on the same day (P < 0.05). It is concluded that the sequential method is as accurate as the single‐dose regimen and carries the advantages of simplicity in the establishment of dose‐response curve for any future CCK‐like agent.