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 (p less than 0.01) and a tendency toward an increased liver-to-background ratio at five minutes with diisopropyl-IDA Tc 99m (p greater than 0.05). Quantification of the relative hepatocyte extraction efficiency indicated a 16% higher extraction efficiency for diisopropyl-IDA Tc 99m (p greater than 0.05). Cumulative three-hour urine collections following injection demonstrated no significant difference in renal excretion in patients with normal total serum bilirubin levels. 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 (p less than 0.01). 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.