Computed Tomography Evaluation of the Arterial Supply to Segment 4 of the Liver

INTRODUCTION: In a setting of living-donor liver transplant and patients undergoing extended hepatic resections for both primary and metastatic liver tumors, preoperative assessment of hepatic arterial anatomy is very important because of the risk of ischemic complications in the event of inadvertent injury to the arterial supply. Anatomical variations in hepatic arterial supply to the liver are very common and seen in nearly half the population. Identifying anomalous origin of segment 4 hepatic artery is vital since this vessel can cross the transection plane and can result in liver ischemia and liver failure. The purpose of our study is to study the variations in hepatic arterial anatomy to segment 4 of the liver in the Indian population. MATERIALS AND METHODS: A retrospective evaluation of 637 consecutive computed tomography (CT) angiograms over a period of 1 year was performed, and we analyzed the arterial supply to segment 4 of the liver. RESULTS: We found that the arterial supply to segment 4 of the liver originated from left hepatic artery (LHA) in majority of cases, 76.3%. LHA along with the accessory LHA supplied this segment in 6.4%, whereas the accessory LHA solely supplied this segment in 0.4%. The right hepatic artery (RHA) was seen to supply this segment in 10.2%. Dual supply with branches from the RHA and LHA was seen in 6.6% of patients. CONCLUSION: Preoperative mapping of segment 4 hepatic arterial supply using CT angiography will act as a roadmap to surgeons as they attempt to carefully dissect and preserve this segments' arterial supply. Depending on the anatomical variation, surgical techniques will vary to ensure safety of segment 4 arterial supply.