Work in progress: clinical evaluation of Tc-99m-trimethylbromo-IDA and Tc-99m-diisopropyl-IDA for hepatobiliary imaging.

Six healthy individuals and six patients with a wide range of hepatobiliary function abnormalities were studied with Tc-99m-trimethylbromo-IDA; all normal subjects and four of the six patients were also studied with Tc-99m-diisopropyl-IDA. Visual evaluation of analog images demonstrated a greater liver-to-kidney ratio for Tc-99m-trimethylbromo-IDA (p less than 0.01). Sampling for radiopharmaceutical in urine at three hours following injection demonstrated that Tc-99m-trimethylbromo-IDA had a lower renal excretion rate than Tc-99m-diisopropyl-IDA regardless of whether hepatocyte function was normal or abnormal (p less than 0.01). There were no significant differences between the two radiopharmaceuticals in hepatocyte extraction efficiency or hepatic parenchymal transit time. It is concluded that the lower rate of renal excretion and, therefore, greater hepatocyte specificity of Tc-99m-trimethylbromo-IDA justifies expanded clinical trials and may make it the radiopharmaceutical of choice for hepatobiliary imaging.