3D CE MR portography is regarded as a safe, quick and robust imaging modality for evaluation of the portal-venous system. This technique has been shown to be advantageous compared to currently used techniques such as ultrasonography, catheter angiography, computed tomography (CT), and non-enhanced MR angiography with TOF and phase contrast (PC) techniques .
There are no major differences between MRA of the abdominal arterial system and MR portog-raphy in terms of patient management, coil selection and MR sequences. After acquisition of a pre-contrast coronal 3D gradient echo dataset, contrast agent is injected and image acquisition commences. Typically, image acquisition on MR por-tography is timed to the arterial vessel system with an additional acquisition delay of 40-60 sec after contrast agent injection prior to acquisition of the portal-venous dataset. At post-processing, the pre-contrast and CE arterial phase datasets are subtracted from the portal-venous phase dataset to enable visualization of the portal-venous system without arterial overlay. MIP reconstruction and multiplanar reformation techniques permit accurate evaluation of the portal-venous system.
The simultaneous availability of coronal source images permits demonstration of 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. In patients with portal hypertension and a history of gastro-esophageal bleeding, it is mandatory to ascertain whether the portal-venous system is patent or if the portal vein or its main branches are throm-bosed .
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