Extrahepatic uptake of 99mTc-phytate: its mechanism and significance in chronic liver disease.

The extrahepatic uptake of 99mTc-phytate was evaluated using scintigrams in 47 patients, including 37 patients with cirrhosis, 7 with presinusoidal portal hypertension, and 3 with idiopathic splenomegaly. In these 47 patients, combined umbilicoportal, hepatic vein, and superior mesenteric artery catheterization was performed. The Kupffer cell uptake of 125Iodinated albumin microaggregates was measured during a single passage through the liver, and this parameter was used as an index of the functional hepatic blood flow. A highly significant negative correlation was found between the extrahepatic uptake of 99mTc-phytate and the hepatic uptake of 125I-albumin microaggregates. However, no correlation was found between the extrahepatic uptake and portal hypertension as evaluated by the porohepatic gradient. The present study strongly suggests that the 99mTc-phytate extrahepatic uptake is mainly due to a failure of the diseased liver to remove colloids and is not related to the degree of portal hypertension. Our data also indicate that 99mTc-phytate liver scan may provide an indirect assessment of the functional hepatic blood supply and might be useful in the follow-up of patients with chronic liver diseases.