Comparison of Tc-99m diethyl-iminodiacetic acid and I-131 rose bengal for hepatobiliary studies in liver-transplant patients: Concise communication.

Previous animal studies indicate that technetium-99m N,..cap alpha..-(2,6-diethylacetanilide)-iminodiacetic acid (/sup 99m/Tc diethyl-IDA) is superior to /sup 131/I rose bengal (/sup 131/I RB) in most, but not all, physiologic parameters. Technetium-99m diethyl-IDA has a faster blood clearance, greater hepatic clearance, and a shorter hepatocyte transit time, but /sup 131/I RB exhibits less renal clearance. We evaluated the relative merits of /sup 99m/Tc-diethyl-IDA and /sup 131/I RB in paired studies in ten liver-transplant patients. Technetium-99m diethyl-IDA images were superior to /sup 131/I RB images in demonstrating: (1) the liver parenchyma, (2) intrahepatic ducts, (3) small-bowel activity early after injection, and (4) in a smaller number of comparisons, colonic activity at 24 hr after injection. In addition, the percentage of dose excreted in the urine in 3 h for both radiopharmaceuticals was measured in 19 patients (total serum bilirubin range: 0.5 to 22.4 mg/dl). The percentage of dose of/sup 99m/Tc diethyl-IDA excreted in the urine averaged 7.5 in patients with normal total bilirubin levels and increased significantly with increasing total bilirubin levels. In the case of /sup 131/I RB, normal patients averaged 4.9% of the injected dose in the urine and there was no increase with increasing total bilirubin levels. It is concludedmore » that (1) /sup 99m/TC diethyl-IDA is superior to /sup 131/I RB for imaging the hepatobiliary system, and (2) renal excretion of /sup 131/I RB, unlike that of /sup 99m/Tc diethyl-IDA, is relatively unaffected by the total serum bilirubin level during the first 3 h after injection.« less