Ablative margin states by magnetic resonance imaging with ferucarbotran in radiofrequency ablation for hepatocellular carcinoma can predict local tumor progression

Our aim was to determine how well ablative margin (AM) grading assessed by magnetic resonance imaging (MRI) with ferucarbotran administered prior to radiofrequency ablation (RFA) predicts local tumor progression in comparison with enhanced computed tomography (CT). 101 hepatocellular carcinomas were treated by RFA after ferucarbotran administration. We performed T2*-weighted MRI after 1 week and enhanced CT after 1 month. The assessment was categorized in three grades: AM(+): high-intensity area with continuous low-intensity rim; AM zero: high-intensity area with discontinuous low-intensity rim; and AM(-): high-intensity area extending beyond the low-intensity rim. AM(+), AM zero, AM(-) and indeterminable were found in 47, 36, 8 and 10 nodules, respectively. The overall agreement rate between MRI and enhanced CT for the diagnosis of AM was 71.3 %. The kappa coefficient was 0.523 (p < 0.001), indicating moderate agreement. Multivariate logistic regression showed that a significant factor for the achievement of AM(+) on MRI was only segment location (odds ratio 5.9, non-segment 4 + 8 vs. segment 4 + 8). The cumulative local tumor progression rates (4.4, 7.6, and 7.6 % in 1, 2, and 3 years) in 47 AM(+) nodules were significantly lower than those (13.9, 33.4, and 41.8 % in 1, 2, and 3 years) in 36 AM zero nodules. A multivariate Cox proportional hazards model identified contiguous vessels (odds ratio 12.0) and AM(+) on MRI (odds ratio 0.19) as independent factors for local tumor progression. AM assessment by MRI using ferucarbotran can predict local tumor progression after RFA and enable early and less invasive diagnosis.