Diffusion-weighted imaging compared to dynamic MRI in early response assessment of locoregional therapy (by trans-arterial chemoembolization & microwave ablation) of hepatocellular carcinoma

Background Purpose of this study is to compare between dynamic contrast-enhanced and diffusion-weighted MRI imaging techniques in early response assessment of hepatocellular carcinoma (HCC) after transcatheter chemoembolization and microwave ablation. Methods Retrospective study was done over a period of 36 months (June 2015–June 2018). The study was conducted on 69 cases; 61 patients were males and 8 were females patients age ranged from 45 to 72 years (median 60). All patients suffered from liver cirrhosis secondary to chronic viral hepatitis. They underwent diffusion-weighted MR imaging and subtraction dynamic MR imaging techniques after trans-arterial chemoembolization (TACE) and microwave ablation (MWA). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall agreement were calculated for both the dynamic and the DWI images. Apparent diffusion coefficients (ADCs) were calculated searching for a cutoff value using the receiver operating characteristic curve (ROC). Results Our study results revealed moderate accuracy of diffusion MRI in the diagnosis of complete ablation (no residue) less than that of dynamic and subtraction sequences with 71.43% sensitivity, 88.52% specificity, 83.3% PPV and 79.4% NPV. This is attributed to that diffusion MR study is not able to detect small enhancing tumor foci that appears clearly on dynamic and subtraction MR studies. Also, these results are attributed to false positive results on diffusion study corresponding to liquefactive necrosis with hemorrhagic component post-ablation. Conclusions Our study concluded that subtraction and dynamic MRI had more accuracy than diffusion compared to our follow-up results. So combined subtraction dynamic MR study and diffusion is the main technique of early evaluation of post-interventional therapy of HCC to avoid pitfalls of diffusion study.