LI-RADS CT/MRI Nonradiation Treatment Response Assessment Version 2024 for Detecting Local Recurrence of Surgically Resected Hepatocellular Carcinoma

<b>BACKGROUND.</b> LI-RADS CT/MRI Nonradiation Treatment Response Assessment (TRA) version 2024 (v2024) specifies that the updated algorithm may be applied for evaluating the surgical margin after resection of hepatocellular carcinoma (HCC). <b>OBJECTIVE.</b> The purpose of this study was to compare detection of local recurrences after surgical resection of HCC between LI-RADS CT/MRI Nonradiation TRA v2024 and the LI-RADS CT/MRI Core version 2018 (v2018) diagnostic algorithm. <b>METHODS.</b> This retrospective study included patients with surgically resected HCC who underwent at least one liver CT or MRI examination performed at least 6 months postoperatively. Two radiologists independently reviewed all postoperative CT and MRI examinations of included patients in separate sessions, assessing the surgical margin by use of LI-RADS CT/MRI Nonradiation TRA v2024 and LI-RADS CT/MRI Core v2018, respectively; a third radiologist resolved discrepancies. Local recurrence was defined by v2024 as LR-TR Viable (i.e., masslike enhancement at the margin, noted in any phase and of any size) and by v2018 as LR-5, LR-M, or LR-TIV. <b>RESULTS.</b> The study included 200 patients (142 men and 58 women; median age, 67 years) with a median follow-up of 30.5 months. Interreader agreement for v2024 categorization was substantial (κ = 0.71). By v2024, LR-TR Viable at the surgical margin was assigned in 56 patients (28.0%) (on the initial postoperative examination in 21 patients, directly after an LR-Nonviable assignment without an intervening LR-TR Equivocal assignment in 31 patients, and after an LR-TR Equivocal assignment in the remaining four patients); the assignments were made after a median of 5.1 months and at a median observation size of 1.5 cm. By v2018, LR-5, LR-M, or LR-TIV was assigned at the surgical margin in 52 patients (26.0%) after a median of 12.0 months (<i>p</i> < .001) and at a median size of 2.1 cm (<i>p</i> < .001). At the time of the 56 initial LR-TR Viable assignments, the categories assigned for v2018 were LR-3, LR-4, LR-5, LR-M, and LR-TIV in 21, 10, 18, three, and four patients, respectively. Upgrading of LR-3 and LR-4 observations to LR-5, LR-M, or LR-TIV occurred after a median of 5.1 and 3.0 months, respectively. <b>CONCLUSION.</b> v2024 detected local recurrence in 28% of patients at an earlier time and at a smaller size than did v2018. <b>CLINICAL IMPACT.</b> The findings support application of v2024 for surgical margin evaluation after HCC resection.