Diagnostic Performance of LI-RADS Treatment Response Algorithm for Hepatocellular Carcinoma: Adding Ancillary Features to MRI Compared with Enhancement Patterns at CT and MRI

P atients with hepatocellular carcinoma (HCC) in- creasingly undergo local-regional therapy (LRT), including radiofrequency ablation and transcatheter arterial chemoembolization, as the first-or second-line treatment and a bridge to liver resection or liver transplantation (LT) (1,2).The pathologic tumor response to LRT is used to predict patient outcome after subsequent surgical resection (3,4) or liver transplantation (5), which makes imaging prediction of pathologic tumor response important for preoperative prognostic classification.Patients who meet the Milan criteria with downstaging of HCC after LRT become potential candidates for liver transplantation (6); therefore, post-LRT imaging assessment of tumor viability can play a critical role in the appropriate allocation of donor livers.The modified Response Evaluation Criteria in Solid Tumors remain the standard imaging criteria for evaluation of tumor response to LRT, taking tumor viability into account through assessment of the arterially enhancing area in the treated lesion (5).For HCCs managed with LRT, the Liver Imaging Reporting and Data System (LI-RADS) introduced a per-lesion categorization algorithm for CT and MRI known as the LI-RADS Treatment Response (LR-TR) algorithm ( 7).Although the LR-TR algorithm and the modified Response Evaluation Criteria in Solid Tumors