Identification of the anterior sectoral trunk with particular reference to the hepatic hilar plate and its clinical importance

Background: At the hilum of the liver, there is a structure called the hilar plate, which is of great surgical importance because all variations in the bile ducts and blood vessels occur within this region. The Rex-Cantlie line does not always pass the point of portal bifurcation. Classifying portal vein (PV) variations based on the shape and origin of anterior sectoral trunk (AST) within the hepatic plate system will be of higher anatomical and surgical value than the conventional method based on PV ramification. Methods: We investigated PV variations in the hilar plate in terms of combinations of 4 hepatic sectoral trunks rather than successive ramification of the PV. The combination patterns of each sectoral trunk were analyzed using data from adult cadaver liver dissection (n = 64) and multi-detector computed tomography (n = 216) of human livers. Results: The AST root position on the hilar plate varies, in contrast to the other sectoral trunks, which are relatively consistent in their root position. Three types of PV variations were identified based on the AST root position. In addition, 4 similar but different shapes (I, Y, V, and U) of AST were identified. Conclusion: Not only the root position in the hepatic hilar plate but also the shape of AST can be considered as the major determinants of PV variations.