The usefulness of motion artifact suppression technique (MAST) in the MRI diagnosis of liver tumors was assessed. Spin-echo with MAST was superior in lesion detection and contrast-to-noise ratio to conventional spin-echo. Its usefulness was verified. As the portal vein is delineated frequently as a high signal area, the portal structure up to the third branches was distinctly visualized. It was found helpful for the segmental diagnosis of the liver. However, careful attention is needed in the diagnosis of portal vein thrombosis.