Basic and clinical studies on hepatobiliary function test with sup(99m)Tc-PI

In these basic and clinical studies, the usefulness of sup(99m)Tc-pyridoxilideneisoleucine, a new hepatobiliary agent, was evaluated for a hepatobiliary function test in comparison with sup(99m)Tc-N-[N-(2,6 dimethylphenyl)carbamoylmethyl] iminodiacetic acid (HIDA) and 131I-rose bengal (RB). The experiments were performed with 2.5 - 5 kg rabbits. Hepatic uptake and the excretion of sup(99m)Tc-pyridoxylidene isoleucine (PI) were earlier than those of 131I-RB. However, biliary excretions of sup(99m)Tc-PI and sup(99m)Tc-HIDA were less than that of 131I-RB, because urinary excretions of sup(99m)Tc-labeled compounds were greater. During the first 2.5 - 5 min, sup(99m)Tc-labeled agents had lower blood levels than 131I-RB. At 6 days after the choledochal ligation, no hepatic uptake of sup(99m)Tc-PI was noted, although 131I-RB concentrated to the liver. Blood retention of sup(99m)Tc-PI might not always reflect hepatobiliary function, especially in the hyperbilirubinemia. On the other hand, hepatograms from a region of interest corresponding to the liver varied with changes in the serum bilirubin level, although no hepatic uptake was detected in the complete obstructive jaundice and severe parenchymal liver disease being over 7 mg/dl in the serum bilirubin level. (author)