Clinical utility of multipolar ablation with a three-dimensional simulator system for patients with hepatocellular carcinoma

Purpose Recently, multipolar RFA has been utilized. Multipolar RFA offers the advantage of providing a large volume of ablation, providing more homogeneous necrosis with a higher rate of pathological complete necrosis. Although very encouraging results have been reported for multipolar RFA, the monopolar technique remains by far the most frequently used technique worldwide. We developed 3D sim-Navigator as a navigation and simulation system. For achieving insertion of electrodes around the tumor in a well-balanced manner, this system appeared very useful. To confirm the efficacy of multipolar ablation with new simulator system for patients with hepatocellular carcinoma by assessing for relapse-free survival and shape of the ablation volume under clinical conditions. Materials and Methods All participants provided written, informed consent, and study protocols were approved by the institutional ethics committee. Twenty-seven patients with 27 nodules were treated by no-touch ablation using the new simulator system. Another 21 patients with 21 nodules treated without the simulator system were enrolled as controls. Ablation was performed without inserting any applicator into the tumor by placing all electrodes around the tumor, if possible. Ablation was started after confirming a well-balanced positioning of electrodes around the tumor using the simulator system. In multipolar ablation, the positional relationships of multiple electrodes were easy to intuitively understand by repeated marking for insertions of the second and third RFA electrodes. The vertical cross-sectional image (C-plane) was utilized. Tumor progression and shape of ablation volume were assessed. Predictive factors of tumor progression were assessed by Cox proportional hazard model. Results No significant differences in clinical characteristics were seen between groups. Mean sphericity was 0.48 ± 0.07 with the 3D sim-Navigator and 0.37 ± 0.07 without the 3D sim-Navigator (P Conclusions Ideal ablation area was acquired by this simulation and navigation system in clinics. This system improved local tumor progression by appropriate insertion of multiple electrodes.