Beyond Diagnosis: Magnetic Resonance Imaging-Based Imaging Biomarkers for Tumor Biology, Prognosis, and Clinical Decision-Making in Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is a biologically heterogeneous malignancy staged according to tumor burden and clinical status. Molecular and histopathologic factors remain unincorporated into current staging systems, as they are usually unavailable because HCC is often diagnosed noninvasively. Emerging evidence indicates that magnetic resonance imaging (MRI) features reflect underlying tumor biology and provide prognostic information beyond diagnosis. MRI can differentiate proliferative-class HCC, which is characterized by aggressive behavior, frequent microvascular invasion (MVI), and poor outcomes, from non-proliferative-class HCC with more favorable biology. Several MRI features, including rim arterial phase hyperenhancement (APHE), non-smooth margins, necrosis, intratumoral arteries, low apparent diffusion coefficient, peritumoral APHE, and peritumoral hepatobiliary phase (HBP) hypointensity, have been associated with aggressive tumor behavior and adverse outcomes. In contrast, capsule appearance, intratumoral fat, and HBP hyperintensity are associated with more favorable biology. Although biopsy is not routinely required when characteristic imaging features of HCC are present, imaging features suggestive of aggressive tumor subtypes may identify patients who could benefit from histologic confirmation for diagnostic clarification, molecular profiling, or treatment planning. Radiomics and artificial intelligence-based analyses further enhance MVI prediction, recurrence risk stratification, and noninvasive molecular characterization. In conclusion, the emerging role of MRI in characterizing tumor biology underscores the growing importance of imaging biomarkers in clinical decision-making and selective biopsy strategies.