Expanding Role of US in Diagnosis of Portal Hypertension and Cirrhotic Complications

Abstract

Color Doppler Ultrasonography (CD-US) has an advantage of being non-invasiveness, so many attempts to investigate the hemodynamic alterations in cirrhosis and the response to medical treatment of portal hypertension as well as morphologic change of liver have been made. In particular, any CD-US parameter that could be a suitable substitute for the invasive current gold standard for assessing portal hypertension by measuring hepatic venous pressure gradient (HVPG) and hepatic fibrosis evaluated by liver biopsy, would be highly desirable. The presence of intrahepatic shunts resulting from portal hypertension can be helpful to diagnosis of portal hypertension and cirrhosis through novel characteristic CD-US index. It has been recently suggested that the extent of abnormality in Doppler hepatic vein (HV) waveform is associated with degree of HVPG as well as severity of hepatic fibrosis, and a change in HV waveform is closely correlated with that in HVPG. Abnormal flattened HV wave form is thought to be due to hemodynamically blunting the effect of variations in central venous pressure during the cardiac cycle, which is arising from increased HV inflow via intrahepatic shunts secondary to portal hypertension. Moreover, under microbubble contrast enhancement, CD-US detection of decreased hepatic vein transit time due to presence of intrahepatic shunts can be useful to assess the severity of portal hypertension and grade of fibrosis. However, for being reproducible and accurate, a cooperative training program of operators with strict examination protocol would be helpful to reduce the rate of intra-and inter-observer variation. Consequently, developments of novel CD-US indices and techniques are ongoing to overcome the limitations of conventional CD-US methods in diagnosis of portal hypertension and cirrhosis, and some of them are enough to potentially allow widespread clinical use.