The American College of Radiology Liver Imaging Reporting and Data System (LI-RADS) standardizes the imaging technique, reporting lexicon, categorization, and management of patients with, or at risk for, hepatocellular carcinoma (HCC). This presentation provides an overview of CEUS LI-RADS Treatment Response Algorithm (TRA), including a lexicon of imaging findings, techniques, and imaging criteria for post-treatment HCC viability assessment. CEUS LI-RADS TRA takes into consideration differences in CEUS appearance of viable HCC and post-treatment changes both within and in close proximity to a Treated Lesion. Due to the high sensitivity of CEUS to vascular flow, post-treatment reactive changes commonly manifest as areas of abnormal perilesional enhancement without washout, especially in the first 3 months after treatment. To improve the accuracy of CEUS for TRA, different diagnostic criteria are used to evaluate for disease viability within and outside of the Treated Lesion margins. Broader criteria for intralesional enhancement increase sensitivity to tumor viability detection. Stricter criteria for perilesional enhancement limit misclassification of post-treatment reactive changes as viable tumor. Finally, a TRA reconciles intralesional and perilesional tumor viability assessment and assigns a single treatment response category: LI-RADS treatment response Nonviable, Equivocal, or Viable.
