Histopathological outcomes of CT-guided high-dose-rate interstitial brachytherapy for HCC and predictive accuracy of the LI-RADS Radiation Treatment Response Algorithm v2024.

OBJECTIVE

To evaluate the histopathological outcomes after CT-guided high-dose-rate interstitial brachytherapy (HDR-BT) in hepatocellular carcinoma (HCC) patients and to assess the performance of the Liver Imaging Reporting and Data System (LI-RADS) Radiation treatment response algorithm (TRA).

MATERIALS AND

METHODS

This retrospective analysis evaluated 19 patients with 29 HCC lesions who underwent HDR-BT before liver transplantation in a single center. Lesions were evaluated for the degree of tumor necrosis on explant histopathology. The association between procedural characteristics and complete pathological necrosis on histopathology was evaluated. The medians of continuous variables were used as cutoff values. The diagnostic value of LI-RADS treatment response (LR-TR) categories was evaluated by two readers using pre-transplantation MR images.

RESULTS

Histopathological evaluation revealed complete pathological necrosis in 19 lesions (65.5%). The remaining 10 lesions all demonstrated more than 50% tumor necrosis and showed clear evidence of apoptotic activity within the residual viable areas, as confirmed by TUNEL staining. Lesions of patients with a longer interval (> 136 days) between HDR-BT and transplantation showed significantly higher rates of complete necrosis (86.7% vs. 42.9%, p = 0.026), suggesting ongoing radiation-induced cell death and potentially therapy-induced senescence beyond the time of histological sampling. No lesion was categorized as LR-TR viable on pre-transplant MRI according to LI-RADS Radiation TRA v2024. All lesions classified as LR-TR nonviable demonstrated complete pathological necrosis on histology.

CONCLUSION

HDR-BT is associated with high rates of complete pathological necrosis in explanted livers, while LI-RADS Radiation TRA demonstrates promising performance in assessing treatment response.

KEY POINTS: Question Histopathological outcomes after CT-guided high-dose-rate brachytherapy (HDR-BT) and the predictive accuracy of the LI-RADS Radiation Treatment Response Algorithm in hepatocellular carcinoma remain insufficiently defined. Findings CT-guided HDR-BT achieves high rates of complete pathological necrosis in HCC lesions, with treatment response accurately predicted by the LI-RADS Radiation TRA. Clinical relevance HDR-BT seems to be an effective bridging therapy for HCC, providing local control and high necrosis rates. LI-RADS Radiation TRA enables accurate, standardized imaging assessment to guide management and optimize timing toward transplantation.