Technetium-99m-iminodiacetic acid organic anions: review of biokinetics and clinical application in hepatology.

Technetium-99m-labeled iminodiacetic acid analogs are a new class of organic anions, taken up and secreted by hepatocyte into hepatic bile by a carrier-mediated organic anion pathway. They provide a new dimension in the assessment of pathophysiology and morphology of the hepatobiliary system. The amount of uptake and the rapidity of its elimination from the liver is dependent upon the structural configuration of the agent as well as the functional integrity of the hepatocyte and the patency of the biliary system. The clinical areas for application are wide and include most of the hepatobiliary diseases. Technetium-99m-iminodiacetic acid, an agent well suited for both planar and single photon tomographic scintigraphy, is ideal for early diagnosis prior to anatomical changes in the hepatobiliary system. The data collection directly from the liver provides quantitation of both regional and global liver diseases. The count-based method for measuring gallbladder emptying overcomes the theoretical disadvantages of geometric tests. Biokinetics and current clinical application of six of the 99mTc-iminodiacetic acid agents are reviewed, and the potential future clinical and research areas of application are indicated.