Hepatic arterial variants on CT angiography: applicability and coverage of the CRL classification system

PURPOSE: Hepatic arterial anatomy exhibits considerable variability with important implications for hepatobiliary surgery, transplantation, and interventional procedures. This study aimed to evaluate hepatic arterial anatomy using the CRL classification system and to assess its applicability and coverage on computed tomography angiography (CTA), with particular emphasis on rare variants. METHODS: A total of 803 abdominal CTA examinations were retrospectively assessed. Hepatic arterial anatomy was categorized according to the CRL classification system based on the origin of the common, right, and left hepatic arteries. The frequency and distribution of each type and subtype were analyzed, and unclassifiable cases were described separately. RESULTS: The most common arterial configuration was Type 1 (standard anatomy), identified in 65.0% (n = 522) of cases. Branching patterns were observed in the remaining cases, with replaced right hepatic artery from the superior mesenteric artery and replaced left hepatic artery from the left gastric artery representing the most frequent variants. Overall, the CRL classification system demonstrated a high classification coverage of 99.5%, with only four cases (0.5%) remaining unclassifiable due to complex arterial configurations. CONCLUSION: The CRL classification system provides a comprehensive and practical framework for evaluating hepatic arterial anatomy using CTA. Its high coverage rate supports its clinical utility in hepatobiliary surgery and transplantation, while the presence of rare unclassifiable patterns suggests potential refinement with additional combination types.