MR Angiography of the Portal Venous System

Abstract

Three-dimensional (3D) contrast-enhanced (CE) magnetic resonance (MR) portography is a quick and robust means of evaluating the portal venous system offering some advantages over currently used imaging modalities including catheter-based digital subtraction angiography (DSA), computed tomography, ultrasonography and non-enhanced MR angiography with time-of-flight (TOF) and phase contrast (PC) techniques [1].With 3D CE MR portography a first-pass study of the mesenteric vasculature is performed (see.VI 3.) after rapid bolus injection of gadolinium-based contrast agent. Repeated sequences allow depiction of the intraand extrahepatic portal venous anatomy. The images can then be reconstructed by means of maximum-intensity-projection (MIP) postprocessing, and a subtraction technique can be employed to eliminate arterial enhancement and demonstrate portosystemic shunts. The coronal source images simultaneously demonstrate parenchymal lesions of the liver, pancreas, biliary tract and spleen. Precise and reliable assessment of the portal venous system in patients with hepatic cirrhosis and portal hypertension is essential before liver transplantation, non-surgical transjugular shunting or surgical portosystemic shunting. Especially in patients with portal hypertension and a history of gastro-esophageal bleeding it is mandatory to determine whether the portal venous system is patent or the portal vein or its main branches are thrombosed [2].