Assessment of the Treatment Response of Hepatocellular Carcinoma to Radiofrequency Ablation Using Dynamic and Diffusion MR Imaging according to LI-RADS v2018 Treatment Response Algorithm

Abstract Background: Hepatocellular carcinoma is the most com-mon primary liver malignancy and considered as the fifth most common cancer worldwide. Resection and liver trans-plantation have a high survival in adequately selected patients, however locoregional ablative therapeutic techniques has several advantages over surgery like hepatic parenchymal preservation and overall have less morbidity and mortality. Aim of Study: The aim of this study was to evaluate the role of diffusion and dynamic MR imaging in the assessment of the treatment response of hepatocellular carcinoma after radiofrequency ablation according to the LI-RADS treatment response v2018. Patients and Methods: A retrospective study included 40 patients with 45 HCC lesions underwent radiofrequency ablation and followed-up by dynamic and diffusion MR imaging. The data were collected from the PACS of Radiology Department, Cairo University Hospitals. The MR images were assessed according to LI-RADS 2018 treatment response algorithm. Results: According to LI-RADS treatment response cri-teria, dynamic MRI has sensitivity of 100%, specificity 95.8%, Positive Predictive Value (PPV) 94.1% and Negative Predictive Value (NPV) 100% compared to sensitivity of 64.3%, specif-icity 95.8%, PPV 90% and NPV 82.1% for the diffusion weighted images in the detection of tumoural viability. Arterial Phase Hyperenhancement (APHE) was found in 87.5% of viable lesions while delayed wash out was found in 100% of the viable lesions. Conclusion: Dynamic MRI is the cornerstone in the assessment of treatment response of hepatocellular carcinoma to radiofrequency ablation. Arterial phase hyperenhancement and delayed wash out are the main criteria for diagnosis of tumoural viability according to LI-RADS treatment response algorithm. Diffusion imaging and ADC measurement are good negative techniques for exclusion of tumoural activity and also can confirm the dynamic findings in viable cases.