Application of LI-RADS CT/MRI Radiation Treatment Response Assessment Version 2024: a study after transarterial radioembolization for hepatocellular carcinoma

Purpose: To compare the performance of the LI-RADS CT/MRI Radiation Treatment Response Assessment (TRA) version 2024 (v2024) after transarterial radioembolization (TARE) for hepatocellular carcinoma (HCC) with that of the LI-RADS CT/MRI TRA version 2017 (v2017). Methods: This retrospective study included patients with HCC treated with TARE followed by hepatic surgery between November 2012 and April 2023 at two tertiary referral centers. Each treated lesion was assigned an LI-RADS treatment response (LR-TR) category based on a consensus reading of three radiologists using both v2024 and v2017. The sensitivity and specificity of the two TRA versions were compared using the McNemar test, with histopathology as a reference standard. Results: A total of 46 (mean age, 56.2 years; 39 men) patients with 46 TARE-treated lesions (23 with incomplete [< 100%] necrosis) were included. The distribution of categories based on v2024 was as follows: LR-TR Nonviable, 52.2% (24/46); LR-TR Nonprogressing, 39.1% (18/46); and LR-TR Viable, 8.7% (4/46). While no category change was noted for LR-TR Nonviable lesions, 16 lesions classified as LR-TR Viable in v2017 were recategorized as LR-TR Nonprogressing in v2024. For predicting histopathologically incomplete necrosis, the LR-TR Viable or Nonprogressing categories of v2024 and the LR-TR Viable or Equivocal categories of v2017 showed equivalent high sensitivity (87.0%; 20/23; 95% confidence interval [CI]: 67.9, 95.5) and specificity (91.3%; 21/23; 95% CI 73.2, 97.6) (all P > 0.99). Conclusion: While applying the updated radiation TRA v2024 resulted in recategorization, its diagnostic performance in predicting tumor viability was comparable to that of TRA v2017.