1Department of Radiology, Stanford, California, USA.
2Department of Radiology, University of Michigan Medicine, Ann Arbor, Michigan, USA.
3Department of Internal Medicine, University of Michigan Medicine, Ann Arbor, Michigan, USA.
4Department of Radiology, University of Toledo Medical Center, Toledo, Ohio, USA.
5Department of Radiology and Hepatology, University of Michigan Medicine, Michigan, USA.
6Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
7Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, USA.
8Department of Radiology, University of North Carolina at Chapel Hill School of Medicine, Chapel Hill, North Carolina, USA.
9Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
10Department of Radiation Oncology, Mayo Clinic Rochester, Rochester, Minnesota, USA.
As the incidence of hepatocellular carcinoma (HCC) and subsequent treatments with liver-directed therapies rise, the complexity of assessing lesion response has also increased. The Liver Imaging Reporting and Data Systems (LI-RADS) treatment response algorithm (LI-RADS TRA) was created to standardize the assessment of response after locoregional therapy (LRT) on contrast-enhanced CT or MRI. Originally created based on expert opinion, these guidelines are currently undergoing revision based on emerging evidence. While many studies support the use of LR-TRA for evaluation of HCC response after thermal ablation and intra-arterial embolic therapy, data suggest a need for refinements to improve assessment after radiation therapy. In this manuscript, we review expected MR imaging findings after different forms of LRT, clarify how to apply the current LI-RADS TRA by type of LRT, explore emerging literature on LI-RADS TRA, and highlight future updates to the algorithm. EVIDENCE LEVEL: 3. TECHNICAL EFFICACY: Stage 2.