Portal venous variations - Prevalence with contrast-enhanced helical CT

Purpose: To review the distribution of intrahepatic portal venous branching in order to determine the prevalence of variations. Material and Methods: We made a retrospective review of 655 contrast-enhanced helical CT (CECT) images of patients referred to our department for upper abdominal CT examination during an 8-month period. Of the 655 patients, 70 were eliminated from the study because of improper opacification of the portal venous system. Variations of portal venous branching in the remaining 585 patients were classified. Results: Of 585 patients, 504 (86.2%) had classical bifurcation of the main portal vein (MPV); 72 (12.3%) had a trifurcation of the MPV, 5 (0.9%) had a right anterior segmental branch originating from the left portal vein (LPV), 2 (0.3%) had an LPV originating from the right anterior segmental branch and 2 (0.3%) had a right posterior segmental branch arising from the MPV. Conclusion: Variations of portal venous branching are common and helical CT is efficacious in identifying these variations.