Prevalence of Hepatic Artery Variations on CT Using Michel and Hiatt Classification: A Retrospective Observational Study

Introduction: The liver, a major abdominal organ, receives a dual blood supply: the portal venous system (70-80%) and the systemic arterial circulation (20-30%). The abdominal aorta supplies the gastrointestinal tract through three major branches: the coeliac axis, the superior mesenteric artery, and the inferior mesenteric artery. However, anomalies during embryogenesis may result in a wide diversity of anatomical variants. Regional data using modern Multidetector Computed Tomography (MDCT) are limited, particularly in the Indian population. Aim: To determine the prevalence of anatomical variations of the common hepatic artery, right hepatic artery, and left hepatic artery in a South Indian cohort using Computed Tomography (CT) imaging. Materials and Methods: The present retrospective observational study was conducted in the Department of Anatomy, PSG Hospitals, Peelamedu, Coimbatore, Tamil Nadu, India, from January 2023 to December 2023. The study population comprised patients who underwent CT whole abdomen scans for various indications during the study period. The primary outcome was to determine the prevalence and patterns of hepatic arterial anatomical variations as visualised on MDCT whole abdomen scans using Michel’s and Hiatt’s classifications. Data were analysed using descriptive statistics. Variations in hepatic artery anatomy were expressed as frequencies and percentages, and the results were presented in tabular form. Results: A total of 1,089 CT abdomen reports yielded 1,094 observations according to Michel’s classification and 1,093 observations according to Hiatt’s classification, due to the presence of more than one variation per individual in some cases. Of the 1,094 observations classified using Michel’s system, 717 (65.54%) demonstrated normal arterial anatomy, while 377 (34.46%) showed variations (Michel types II-X or Hiatt types II-VI and unclassified variants). Conclusion: The present retrospective analysis highlights the presence of hepatic arterial variations in a significant proportion of the cohort, underscoring the importance of careful preoperative radiological evaluation to support accurate diagnosis, surgical planning, and the prevention of iatrogenic complications during interventional procedures.