Intrahepatic portal venous variations: Demonstration by helical CT during arterial portography

Purpose: We assessed the prevalence and types of intrahepatic portal venous variations by helical computed tomography performed with arterial portogra phy (CTAP). Methods: In 192 patients without evidence of vascular invasion or distortio n, CTAP images were reviewed retrospectively to identify portal venous vari ations. Results: Of the 192 patients examined, 10 (5.2%) had trifurcation, 5 (2.6%) had a right posterior segmental branch arising from the main portal vein, 5 (2.6%;) had an absence of the horizontal segment of the left portal vein, and 1 (0.5%) had an absence of the left lateral segmental portal branch. O f the patients without a horizontal segment, two had a right-sided ligament um teres associated with malposition of the gallbladder, while another had complete ramification of intrahepatic portal brunches from an umbilical vei n-like segment. In the patient missing the left lateral segmental branches, the right portal vein segments were subcapsularly located. Conclusion: Variations of the intrahepatic portal veins can be recognized o n CTAP imaging.