Radiological Assessment and Therapeutic Evaluation in Hepatocellular Carcinoma: Differentiation and Treatment Response with Japanese Guidelines

The liver is supplied by a dual blood flow system consisting of the portal vein and hepatic artery. Imaging techniques for diagnosing hepatocellular carcinoma (HCC) have been developed along with blood flow imaging, which visualizes the amount of arterial and portal blood flow. The diagnosis of HCC differentiation is important for early-stage liver cancer screening and determination of treatment strategies. Dynamic computed tomography/magnetic resonance imaging (MRI) includes blood flow imaging and MRI with contrast-enhanced ultrasound and liver-specific contrast agents are used in combination. In addition, unlike the Response Evaluation Criteria in Solid Tumors (RECIST) (version 1.1), which is the standard for determining treatment efficacy for solid tumors in general, tumor necrosis is generally considered a treatment effect in HCC, and the modified RECIST and Liver Cancer Direct Effectiveness Criteria (RECICL) are widely used. Familiarity with the definitions, criteria, and potential challenges of the mRECIST and RECICL is essential for their effective application in clinical practice. This review integrates the latest advancements in systemic treatments and imaging techniques, including the role of LI-RADS and updates on molecular-targeted therapies such as regorafenib, supported by some systematic review and meta-analysis.