Peripheral obstruction of intrahepatic portal vein branches was detected by dynamic sequential computed tomography during arterial portography and subsequently confirmed surgically in 9 patients with hepatic neoplasm (7 hepatocellular carcinomas, 1 cholangiocarcinoma, and 1 metastatic lymphadenopathy from gastric carcinoma). In 1 patient, 2 obstructed segments were seen. Eight of these 10 segments showed more dense staining than other regions of the liver during infusion hepatic angiography. Retrograde opacification of the peripheral venules of the obstructed portion was seen in 2 of these 8 segments. This pattern was attributed to trans-sinusoidal or peripheral arterioportal shunting. In 5 cases, the segmental staining obscured the tumor stain, making the tumor appear larger than it actually was or causing it to be missed altogether.