The value of dynamic subtraction MRI technique in the assessment of treatment response of hepatocellular carcinoma to transcatheter arterial chemoembolization

BackgroundHepatocellular carcinoma is considered to be the fifth most common cancer worldwide. Resection and liver transplantation have a high survival in the correct clinical scenarios; however, locoregional therapy has many advantages over tumor resection like preservation of hepatic parenchyma and overall less morbidity and mortality. Our aim was to present the role of dynamic subtraction MRI technique in the assessment of treatment response of hepatocellular carcinoma to transarterial chemoembolization.MethodsThe study consisted of 43 patients with 55 hepatocellular carcinoma lesions who underwent transarterial chemoembolization procedure and followed up by dynamic MRI of the liver with post processing to obtain subtraction images 1-1.5months after the procedure. If no signs of disease activity, another follow up study was preformed 2-4months later. Five patients were excluded due to misregistration artifact at the subtraction images. The final cohort is 38 patients having 50 lesions. Precontrast T1, T2, dynamic contrast enhanced, and diffusion-weighted images were acquired. Subtracted dynamic images were created on the workstation. Sequences were assessed by three experienced readers in hepatic imaging. The sensitivity, specificity, positive predictive value, negative predictive value, 95% confidence interval, and overall agreement were calculated for the dynamic and subtracted dynamic images.ResultsThe subtraction images have sensitivity of 96%, specificity of 100%, PPV of 100%, and NPV of 100% Compared to 96%, 100%, 100%, 96%, and 96%, 100%, 100% 96% for the three readers respectively. On the other hand, the dynamic images has sensitivity of 92%, specificity of 96%, PPV of 95%, and NPV of 92.3% compared to 92%, 96%, 95%, 92.3% and 80%, 68%, 71.4%, and 77.2% for the three readers respectively.ConclusionSubtraction technique is a useful confirmative tool as it had higher sensitivity, specificity, PPV, and NPV values compared to the dynamic and diffusion images with high level of agreement between the readers and also associated with significantly higher reader confidence levels.