Abstract No. 88 Radiologic-Pathologic Correlation of Hepatocellular Carcinoma Treated with Microwave Ablation under Hepatic Angiography and CBCT Guidance

The goal of this study was to retrospectively compare the radiologic tumor response rates by mRECIST to pathologic response rates in all patients who underwent single treatment microwave ablation (MWA) with or without transarterial embolization for hepatocellular carcinoma (HCC) prior to liver explantation. From 2019 to 2021, twenty-four patients (63 ± 8.4 years, 20/24 male) with 32 HCC lesions underwent liver explantation (23 transplants, 1 hepatectomy) after being treated with MWA under angiography and cone-beam CT (CBCT) guidance. Same-session transarterial bland or chemoembolization was performed at the discretion of the interventionalist. Lesions were followed with MRI or CT every 1-3 months until transplant. Radiologic response was determined by a fellowship-trained abdominal radiologist using mRECIST. Pathologic response was determined by pathology at liver explant. Patients were excluded from correlation if they were re-treated for incomplete radiologic response prior to transplant. Mean interval from ablation to transplant was 9.1 ± 5.2 months with an average baseline lesion size of 2.1 ± 0.7 cm (0.8-3.8 cm). Same-session transarterial embolization was performed on 11/32 (34%) lesions. Six of the lesions were excluded from the pathologic correlation because the patients underwent subsequent treatment for incomplete radiologic response prior to transplantation (2 TACE, 2 90Y radioembolization, 2 repeat MWA). The overall complete radiologic response (CRR) rate from a single ablation treatment was 25/32 (78%). On most recent follow-up imaging prior to transplant, 25/26 (96.2%) lesions showed CRR with mean interval between last imaging and transplant of 1.9 ± 1.3 months (0.2-4.9 months). On explant pathology, 16/25 (64.0%) lesions showed complete pathologic response, with one lesion not being mentioned in the pathology report. Despite having an excellent imaging response after HCC microwave ablation, there are still a significant number of patients that have undiagnosed residual tumor disease on explanted liver evaluation. Microwave ablation using hepatic angiography and CBCT guidance shows similar response rates to other guidance techniques, with the benefit of being able to perform single session treatments.