QUANTITATION OF PORTOSYSTEMIC SHUNTING IN DOGS BY ULTRASOUND-GUIDED INJECTION OF TC-99M-MACROAGGREGATES INTO A SPLENIC VEIN

A technique is described for the ultrasound-guided injection of Tc-99m -macroaggregates into a splenic vein in order to quantitate portosyste mic collateral circulation. The fraction of portal blood by-passing th e liver was derived from the radioactivity trapped in the liver and lu ngs and was expressed as the shunt index (SI). The method was tested i n healthy dogs without shunting, and in dogs with single hereditary po rtosystemic shunts before and one month after surgical closure of the shunt. The mean SI was 0.01 (range 0.01 to 0.05) in healthy dogs and 0 .94 (0.69 to 1.00) in dogs with hereditary shunts. After partial closu re of the shunts the SI decreased to 0.25 (0.03 to 0.70). There was a significant positive correlation between the logarithms of the concent ration of ammonia in plasma and the SI (r=0.87, P<0.001).