Assessment of portosystemic shunt patency and function with magnetic resonance imaging.

Magnetic resonance imaging (MRI) was performed in seven patients before and after portosystemic shunting to evaluate venous changes accompanying nonselective and selective shunt construction. The size and number of the intrahepatic portal and hepatic veins, left perirenal veins, and left upper quadrant varices were evaluated at MRI before and after shunt construction. MRI correctly diagnosed patent shunts in all seven patients. A marked decrease in the size of intrahepatic veins after a total or nonselective shunt suggests adequate portal vein and variceal decompression. Dilatation of left perirenal veins in the presence of a patent mesorenal or splenorenal shunt suggests hypertension of the left renal vein and possibly inadequate decompression of esophageal varices.