A Ga-68-labeled tetrabromophthalein (Ga-68 BP-IDA) for positron imaging of hepatobiliary function: concise communication.

We describe the chemical synthesis of an iminodiacetic-acid-substituted tetrabromo-o-cresolphthalein (BP-IDA), which complexes Ga-68 tightly. The liver uptake, bile excretion, and urinary excretion of the complex were examined in rats. Maximum liver uptake reached 60%, and 1-hr cumulative bile excretion was 75% of injected dose. Urinary excretion in rats with ligated common bile duct remained below 1%. Competitive action of exogenous bilirubin on hepatobiliary excretion of the Ga complex was less pronounced than that of bromosulfophthalein. The absolute activity determination of the positron emitter Ga-68, the high accumulation in the liver, the low urinary excretion, and the weak competition from exogenous bilirubin are promising features of this radiopharmaceutical for the quantitative study of hepatobiliary function.