Reproducibility of LI-RADS treatment response algorithm for hepatocellular carcinoma after locoregional therapy

Purpose: To determine inter-reader agreement in categorizing hepatocellular carcinoma (HCC) treated with locoregional therapy using the Liver Imaging Reporting and Data System (LI-RADS) treatment response (LR-TR) algorithm. Materials and methods: A total of 93 patients with a total of 112 HCC nodules that were treated using thermal ablation or transarterial chemoembolization were prospectively included. There were 79 men and 14 women with a mean age of 55 +/- 2.6 (SD) years (range: 48-63 years). All patients underwent magnetic resonance imaging (MRI) examination of the liver and MR images were analyzed by two independent observers. Treated HCC nodules were categorized into four groups according to LR-TR scoring system including: (i)LR-TR non-evaluable (treated, response not evaluable); (ii) LR-TR nonviable (treated, probably or definitively not viable); (iii) LR-TR equivocal (treated, equivocally viable) and (iv) LR-TR viable (treated, probably or definitively viable). The inter-observer agreement in LR-TR categorization was assessed using the kappa statistics. Results: There was excellent inter-observer agreement between the two reviewers for overall treated HCC according to LR-TR algorithm (kappa = 0.938; 95% CI: 0.89-1.00; P = 0.001) with 97.31% agreement. The LR-TR categories by both reviewers were non-viable (77/112; 69.6% and 76/112; 67.9%), viable (30/112; 26.8% and 32/112; 27.7%) and equivocal (5/112; 4.4% and 4/112; 3.6%). There was excellent inter-observer agreement for LR-TR nonviable (kappa = 0.938; 95% CI: 0.87-1.0; P = 0.001) with 97.3% agreement, LR-TR viable (kappa = 0.955; 95% CI: 0.89-1.00; P = 0.001) with 98.2% agreement and good inter-observer agreement for LR-TR equivocal (kappa = 0.700; 95% CI: 0.28-1.0; P = 0.001) with 97.3% agreement. Conclusion: LR-TR algorithm conveys high degrees of inter-observer agreement for the evaluation of treatment response of HCC after thermal ablation and transarterial chemoembolization. (C) 2020 Societe francaise de radiologie. Published by Elsevier Masson SAS. All rights reserved.