Anatomical variations of the hepatic artery: a closer view of rare unclassified variants

Abstract

Background: defining the hepatic artery anatomy is of great importance for both surgeons and radiologists. Michel classification was designed to classify hepatic artery variations. Nevertheless, there are variations that do not fit into this classification. In this study, we aim to define the incidence of all variations in a healthy liver donor by reviewing their CT scan with special emphasis on variations that do not fit in any of the Michel classes. Materials and methods: a retrospective analysis of CT scan of donors and potential liver donors who were evaluated by triphasic CT scan. The CT scans were reviewed independently by a radiologist and two transplant surgeons. Cases that did not fit in any of the Michel classes were classified as class 0. Results: out of 241 donors, 210 were classified within the Michel classification, of which 60.9 % were class I and 9.1% class II. Thirty-one donors (12.9%) classified as class 0. Of which, nine, three, two and three had replaced right hepatic artery from pancreaticoduodenal artery, gastroduodenal artery, aorta and celiac artery, respectively. Two and 6 donors had accessory right hepatic artery from pancreaticoduodenal artery and gastroduodenal artery respectively. Segment 4 artery originated from left and right hepatic artery in 56.8% and 31.9%, respectively. Conclusions: a great caution should be taken when evaluating the hepatic artery anatomy, clinicians should anticipate and be familiar with the rare unclassified variations of the hepatic artery.