LI-RADS Nonradiation Treatment Response Algorithm Version 2024: Diagnostic Performance and Impact of Ancillary Features.

Abstract

Background: LI-RADS Treatment Response Algorithm (TRA) version 2024 (v2024) introduced separate algorithms for detecting hepatocellular carcinoma (HCC) viability after radiation and nonradiation locoregional therapies (LRT). The nonradiation algorithm incorporated MRI-based ancillary features to optionally upgrade lesions from LR-TR Equivocal to LR-TR Viable. Objective: To compare the diagnostic performance of LI-RADS Nonradiation TRA v2024 with LI-RADS TRA version 2017 (v2017) and modified RECIST (mRECIST) for evaluating HCC response to LRT on MRI, with attention to the impact of ancillary features. Methods: This retrospective study included 231 patients (198 male, 33 female; median age, 56 years) who underwent LRT for HCC followed by liver resection or transplant between January 2017 and December 2022. Two radiologists (R1, R2) independently evaluated treated lesions (n=306) using LI-RADS Nonradiation TRA v2024, LI-RADS TRA v2017, and mRECIST. Lesions were classified as showing pathologic viability (n=249) or complete pathologic necrosis (n=57) based on curative surgery pathology. Diagnostic performance for pathologic viability was compared using Bonferroni-adjusted McNemar tests, classifying LR-TR Equivocal assessments as test negative. Results: Sensitivity, specificity, and accuracy for LI-RADS Nonradiation TRA v2024 with ancillary features were 85.5%, 75.4%, and 83.7% (R1), and 87.2%, 63.2%, and 82.7% (R2); for LI-RADS Nonradiation TRA v2024 without ancillary features were 81.1%, 78.9%, and 80.7% (R1), and 80.3%, 78.9%, and 80.1% (R2); for LI-RADS TRA v2017 were 79.9%, 82.5%, and 80.4% (R1), and 79.1%, 79.0%, and 79.1% (R2); and for mRECIST, were 83.9%, 54.4%, and 78.4% (R1), and 78.2%, 40.4%, and 78.4% (R2). LI-RADS Nonradiation TRA v2024 with ancillary features showed higher sensitivity and accuracy than LI-RADS Nonradiation v2024 without ancillary features (both readers); higher sensitivity than LI-RADS TRA v2017 (both readers); higher specificity than mRECIST (both readers); and higher accuracy than LI-RADS TRA v2017 (R2) (p<.008); remaining comparisons between LI-RADS Nonradiation TRA v2024 with ancillary features and other systems were not significant (p>.008). Conclusion: LI-RADS Nonradiation TRA v2024 showed good diagnostic performance in detecting pathologic viability. Ancillary features yielded improved sensitivity and accuracy without significant change in specificity. Clinical Impact: Use of LI-RADS Nonradiation TRA v2024 with ancillary features is recommended for guiding prognostic assessments and treatment decisions after LRT.