Clinical comparison of diisopropyl-IDA Tc 99m and diethyl-IDA Tc 99m for evaluation of the hepatobiliary system

Thirty-one patients with a wide range of hepatobiliary function and clinical diagnoses were studied with both diisopropyl-IDA Tc 99m and diethyl-IDA Tc 99m. Images were similar except for an increased liver-to-kidney ratio with diisopropyl-IDA Tc 99m and a tendency toward an increased liver-to-background ratio at five minutes with diisopropyl-IDA Tc 99m. Quantification of the relative hepatocyte extraction efficiency indicated a 16% higher extraction efficiency for diisopropyl-IDA Tc 99m. Both radiopharmaceuticals demonstrated increasing renal excretion with increasing total serum bilirubin levels; however, renal excretion of diisopropyl-IDA Tc 99m increased more slowly than excretion of diethyl-IDA Tc 99m. We conclude that, while the overall differences between these two radiopharmaceuticals are small, diisopropyl-IDA Tc 99m is superior because of a lower renal excretion rate in patients with decreased hepatocyte function