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- 1/2 ) 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 clinician's need satisfactorily.