Arterial-Phase Enhancement Patterns of Hepatocellular Carcinoma: From Pathologic Background to Prognostication and Treatment Response

Arterial-phase hyperenhancement (APHE), which reflects the hemodynamic shift toward an unpaired arterial supply during hepatocarcinogenesis, is one of the most important imaging features for noninvasive diagnosis of hepatocellular carcinoma (HCC). Although the classic non-rim APHE remains the cornerstone of diagnosis, various enhancement patterns have emerged as critical biomarkers for tumor biology and prognosis. This review provides a comprehensive overview of APHE, tracing its historical development alongside technical advancements in angiography, computed tomography, and magnetic resonance imaging, and explores the pathological and genetic backgrounds of APHE. We categorized distinct enhancement phenotypes, including rim APHE, Kawamura classification, arterial-phase hypoenhancing component, intratumoral artery, and arterial-phase peritumoral enhancement. These patterns serve as imaging surrogates for aggressive clinicopathological traits, such as microvascular invasion, the macrotrabecular-massive subtype, the vessels encapsulating tumor cluster pattern, and TP53 mutation. Furthermore, we discuss how these arterial enhancement patterns guide treatment strategies and predict outcomes of surgical resection, locoregional therapies, and contemporary systemic treatments. Understanding the relationship between diverse enhancement patterns and HCC biology is vital for optimizing therapeutic decision-making.