Value of CT and MR Imaging in Assessment of Loco-regional Ablated Hepatocellular Carcinoma using LI-RADS Treatment Response Algorithm (version 2018)

Aim: The aim of this work is to evaluate the role of multiphasic CT and dynamic contrast enhanced MRI using LI-RADS treatment response algorithm (version 2018) and the added values of diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps in the assessment of loco-Regional ablated Hepatocellular Carcinoma (HCC). Methods: This study included 45 patients with 50 loco-Regional ablated HCC lesions. All patients underwent multiphasic CT scan, diffusion weighted and dynamic contrast enhanced MRI. The reference standards for assessment were based on serum alpha-fetoprotein level and dynamic contrast enhanced MRI. Results: Multi-phasic CT had moderate sensitivity (87.5%) and high specificity (100%) for assessment of HCC LI-RADS treatment response algorithm. Dynamic contrast enhanced MRI had high sensitivity (100%) and specificity (100%) for the assessment of HCC LI-RADS treatment response algorithm. The sensitivity and specificity of DWI to diagnose HCC malignant residual or recurrence were 93.7% and 100%, respectively, with very good performance. The mean ADC values of the malignant residual or recurrence were significantly lower than that of benign post-ablation tissue changes areas and the best ADC cutoff value for differentiation between viable and nonviable lesions was 1.1x10^-3 mm²/s. Conclusion: Performance of dynamic contrast enhanced MRI is better than that of multiphasic CT in the assessment of LIRADS treatment response algorithm. DWI and ADC maps could be used as ancillary methods for differentiation between viable and non-viable loco-regional ablated HCC lesions and should be included in LR-TR treatment response algorithm.