USE OF TC-99M SULFUR COLLOID TO EVALUATE CHANGES IN RETICULOENDOTHELIAL FUNCTION IN DOGS WITH EXPERIMENTALLY-INDUCED CHRONIC BILIARY-CIRRHOSIS AND PORTOSYSTEMIC SHUNTING

Technetium-99m sulfur colloid scintigraphy was used to study alteratio ns of reticuloendothelial function in 7 dogs with experimentally induc ed biliary cirrhosis and portosystemic shunting. Scintigraphic studies were performed before and 6 weeks after common bile duct ligation. Ra diocolloid plasma clearance rate was determined by measuring activity in plasma samples and by analyzing the rate of liver uptake on dynamic scintigraphic image sequences. Percentage of uptake in the liver, spl een, and lungs, as well as the ratio of hepatic-to-extrahepatic uptake , was determined from static equilibrium images. Relative to preoperat ive values, there were significant decreases in plasma clearance rate, percentage of liver uptake, and ra tio of hepatic-to-extrahepatic upt ake and significant increases in percentage of spleen and lung uptake on postoperative studies. The mechanism of technetium-99m-labeled sulf ur colloid extraction by the liver is different from that of other rad iocolloids; it does not require active phagocytosis or pinocytosis. Th us, liver uptake of this tracer principally reflects effective liver b lood now. Portosystemic shunting was documented in these dogs at the t ime of the postoperative radiocolloid scans, and we believed was respo nsible for the decrease in liver reticuloendothelial activity. Possibl e mechanisms for the increased splenic and pulmonary reticuloendotheli al activities are discussed.