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

Simple Summary: Unlike RECIST (version 1.1), which is the standard for assessing the treatment efficacy for solid tumors, tumor necrosis is considered a marker of the treatment effect in HCC. mRECIST, which considers tumor necrosis, and the Liver Cancer Treatment Direct Effectiveness Criteria (RECICL) are widely used. There are notable differences between one-dimensional and two-dimensional measurements in mRECIST and RECICL, and their practicality and usefulness are controversial. After fully understanding the characteristics and problems of each method, diagnostic imaging physicians must focus on the imaging modality and criteria that should be used to determine the effectiveness of the method. Furthermore, the inclusion of LI-RADS provides a standardized framework for evaluating HCC and supports consistent diagnostic and therapeutic decision-making. Given the availability of several drugs, predicting the efficacy of systemic chemotherapy for HCC is currently a clinical topic. However, the role of CT is limited. Recently, attempts have been made to detect Wnt/β-catenin mutation/activation in HCC using Gd-EOB-DTPA enhanced MRI (EOB-MRI), and future developments are expected in terms of predicting efficacy. For instance, regorafenib has demonstrated survival benefits in patients previously treated with sorafenib, as highlighted in a recent systematic review and meta-analysis. Additionally, atezolizumab combined with bevacizumab has emerged as a first-line treatment for unresectable hepatocellular carcinoma. 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. [ABSTRACT FROM AUTHOR]