Clinical uses include Detecting portal hypertension (eg, indicated by significant collateral flow and the direction of flow, increased diameter of the portal vein to > 13 to 15 mm) Assessing the patency of liver shunts (eg, surgical portacaval, percutaneous transhepatic) Evaluating portal vein patency before liver transplantation and detecting hepatic artery thrombosis after transplantation Detecting unusual vascular structures (eg, cavernous transformation of the portal vein) Assessing tumor vascularity before surgery Computed tomography (CT) CT is commonly used to identify hepatic masses, particularly small metastases, with a specificity of > 80%.