Unidirectional Ablation Electrode to Minimize Thermal Injury During Radiofrequency Ablation: An Experimental Study in an Ex Vivo Bovine Liver Model

Abstract

Purpose To modify the direction of radiofrequency (RF) ablation and to find optimal technical parameters using a partially insulated electrode. Materials and Methods The authors developed a unidirectional ablation electrode (UAE) by partial insulation of a 1-cm active electrode tip. Each electrode produced 60 ablation zones using insulation of the active tip (270°, group A; 180°, group B; and noninsulated, group C). In each group, six subgroups were created by combining the RF powers (5 W, 10 W, and 20 W) and ablation duration (6 minutes and 12 minutes). Technical success was determined when a half-moon–shaped ablation zone was achieved. The volumes of the technical success zone (Vs) and the technical failure zone (Vf) were measured. Results Technical success was achieved in all 10 cases using a 270° insulated electrode with a 5-W/6-minute parameter. The mean Vs of group A was significantly smaller than the mean Vs of either group B or group C ( P = .003 and P < .001). The mean Vf of group A was significantly smaller than the mean Vf of group B, which was smaller than that of group C ( P < .001). Conclusions A UAE with a partially insulated tip can modify the ablation zone, especially when using 270° insulation with a 5-W/6-minute parameter.