The 2024 LI-RADS treatment response update: practical reporting after non-radiation and radiation locoregional therapies for hepatocellular carcinoma

This review critically appraises the 2024 Liver Imaging Reporting and Data System (LI-RADS) Treatment Response Algorithm (TRA), which introduces separate non-radiation and radiation treatment response pathways and optional MRI ancillary features, and provides evidence-based guidance for clinical implementation. The updated framework addresses key limitations of the prior algorithm, including moderate sensitivity for residual viable hepatocellular carcinoma (HCC), ambiguity of the Equivocal category, and overcalling after radiation therapy. The 2024 update simplifies viability assessment by emphasizing mass-like enhancement as the dominant sign of residual tumor, introduces a radiation-specific Nonprogressing category based on interval behavior, and allows cautious use of diffusion-weighted and T2-weighted MRI ancillary features in selected non-radiation cases. These changes are expected to improve earlier detection of clinically relevant residual disease while reducing false-positive viable calls after radiation-based therapies. Successful implementation requires high-quality imaging, treatment-specific reporting, multidisciplinary review, and awareness of current scope limitations, particularly in patients receiving systemic or combined therapies. CRITICAL RELEVANCE STATEMENT: The LI-RADS v2024 update critically assesses prior flaws by establishing separate non-radiation and radiation treatment response algorithms, directly advancing clinical practice by reducing false-positive viable calls and standardizing surveillance after complex therapies. KEY POINTS: Update resolves inconsistency by establishing separate algorithms for non-radiation and radiation therapies, significantly reducing false-positive "Viable" calls after radiation treatment. Viability criteria are streamlined to rely on mass-like enhancement and optionally include DWI/T2 ancillary features, improving sensitivity for early recurrence detection. These ancillary features require cautious interpretation to minimize false-positive viable calls. Viable lesions prompt intervention, while Nonprogressing lesions warrant close, standardized 3-month surveillance to confirm definitive local control. Typically, short-interval follow-up is performed at ~3 months, but the optimal stability threshold remains undefined.