[Duplex ultrasound of the liver and portal vein system]

Duplex ultrasound allows direct access to portal venous and hepatic vein hemodynamics. This method has been accepted as a reliable procedure to detect portal and splenic venous thrombosis, Budd-Chiari's syndrome, portosystemic collateralisation and changes in the portal venous blood flow direction with a high rate of sensitivity. Besides these qualitative findings Doppler flowmetry allows quantitative measurement of portal venous blood flow velocities. The estimation of portal hypertension and the prediction of the risk of variceal bleeding by quantitative Doppler flowmetry is of increasing clinical importance. In monitoring the efficiency of medicational prophylaxis against gastrointestinal bleeding is also helpful. Duplex ultrasound can be used to evaluate the function of portocaval shunts including the intrahepatic stent shunt as well as to detect vascular complications after liver transplantation. Furthermore the method is gaining importance in the diagnosis and monitoring of therapy of acute liver transplant rejection. In case of liver tumors duplex ultrasound is of value for tumor staging and provides information about the dignity on the basis of perfusion patterns.