Receptor index via hepatic asialoglycoprotein receptor imaging: correlation with chronic hepatocellular damage

Galactosyl human serum albumin is a newly developed receptor-binding agent, specific for the asialoglycoprotein receptor, which resides exclusively on the plasma membrane of mammalian hepatocytes. The receptor-binding agent was synthesized by the covalent coupling of carbohydrate units to human serum albumin. The clinical utility of technetium-99m-labeled galactosyl human serum albumin was evaluated in six control subjects with normal livers and in 50 patients with chronic liver disease. The parameter, receptor index, was derived from liver and heart time-activity data and is the ratio of radioactivity of the liver over the radioactivity of the liver plus the heart at 15 min after the intravenous injection of 3 mg of labeled ligand. Values for the receptor index in the control subjects and in patients with mild, moderate, and severe liver disease were 0.936 +/- 0.015, 0.909 +/- 0.034, 0.848 +/- 0.070, and 0.669 +/- 0.085, respectively. Good correlations were obtained between the receptor index and conventional liver function tests, such as the Child-Turcotte criteria score (rs = -0.776, p = 0.0001), prothrombin time (r = 0.736, p = 0.0001), and the plasma disappearance rate of indocyanine green (r = 0.805, p = 0.0001). These significantly high correlations of the receptor index with classical indicators of hepatic functional reserve suggest that the receptor index is a potentially practical and reliable diagnostic method for estimating the functioning hepatocyte mass and for assessing liver function.