Assessment of ablative margin after radiofrequency ablation for hepatocellular carcinoma; comparison between magnetic resonance imaging with ferucarbotran and enhanced CT with iodized oil deposition.
Our aim was to investigate whether magnetic resonance imaging (MRI) with ferucarbotran administered prior to radiofrequency ablation could accurately assess ablative margin when compared with enhanced computed tomography (CT) with iodized oil marking. We enrolled 27 patients with 32 hepatocellular carcinomas in which iodized oil deposits were visible throughout the nodule after transcatheter arterial chemoembolization. For these nodules, radiofrequency ablation was performed after ferucarbotran administration. We then performed T2-weighted MRI after 1 week and enhanced CT after 1 month. T2-weighted MRI demonstrated the ablative margin as a low-intensity rim. We classified the margin into three grades; margin (+): high-intensity area with a continuous low-intensity rim; margin zero: high-intensity area with a discontinuous low-intensity rim; and margin (-): high-intensity area extending beyond the low-intensity rim. In 28 (86%) of 32 nodules, there was agreement between MRI and CT. The overall agreement between for the two modalities in the assessment of ablative margin was good (κ=0.759, 95% confidence interval: 0.480-1.000, p<0.001). In four nodules, ablative margins on MRI were underestimated by one grade compared with CT. MRI using ferucarbotran is less invasive and allows earlier assessment than CT. The MRI technique performed similarly to enhanced CT with iodized oil marking in evaluating the ablative margin after radiofrequency ablation.