Hepatocellular Carcinoma Response to Local Regional Therapy; Correlations between Pre-Liver Transplants Imaging and Explant Pathology

Background/Aim: Modified Response Evaluation Criteria in Solid Tumors (mRECIST) were developed to assess the response to treatment in patients with HCC, based on measuring the amount of viable tumor using dynamic imaging (CT/MRI). Our aim to compare the estimated viable HCC after locoregional therapy (LRT) by CT imaging and prior to liver transplant to the histopathological assessment of viable HCC in the hepatic explant. Methods: We prospectively evaluated 44 patients with HCC who underwent both LRT and liver transplantation at London health science center. Using mRECIST criteria, the response to LRT was assessed by two blinded radiologists and the percentage of necrosis was reported separately for the reference CT (rCT) done after the last LRT and prior to liver transplantation. The report obtained from each radiologist was combined then was compared to the findings of an expert pathologist reporting on viable tumour present and tumour necrosis in the hepatic explants. Both parties were blinded to prevent bias in the results. Results: A total of forty-one transplant recipients fulfilled the inclusion criteria for the study. At time of listing 100% were within total volume criteria, 86% within UCSF, and 68% within Milan. The average time from the last reference CT scan to liver transplant was 57.7 days; the average time from last LRT to reference CT was 72.5 days. Thirty-four recipients (83%) had accurate assessment for necrosis (mRECIST) within 20% comparing rCT to explant (i.e. concordant). Ninteen, 19 (46%) of the 41 predicted 100% concordance. Only 7/41 (17%) had a poor concordance (>50%) between histology and reference CT images. positive correlation was detected with the correlation coefficient is calculated as 0.5723. Our study demonstrated CT-pathologic correlation in predicting number and size of tumors with Correlation coefficient 0.64 and 0.31, respectively. However, there was poor correlation in predicting total volume with correlation coefficient is calculated as 0.014. Conclusion: Dynamic CT is an accurate tool to evaluate the tumour response prior to liver transplantation and the likelihood of underestimating the tumour burden is low. With expert radiologists and pathologists, the correlation is acceptable and supports the ongoing use of frequent dynamic imaging to evaluate responses to LRT and determining transplant eligibility.