Ex vivo comparison between thyroid-dedicated bipolar and monopolar radiofrequency electrodes

This study evaluated the characteristics of a thyroid-dedicated bipolar RF electrode (BRFE) and compared its ablation performance with that of monopolar RF electrodes (MRFEs) in normal bovine liver blocks.

BRFE was tested on 60 bovine liver blocks with six different time-power combinations, applying 20, 30 and 40 W for 60 and 120 s. Subsequently, BRFE and MRFEs with 0.5-, 0.7- and 1-cm active tips were applied on 160 bovine liver blocks, creating 16 time-electrode combinations (10, 30, 60 and 120 s). The ablation characteristics, RF efficacy and true RF efficacy of each electrode group were then evaluated and compared. True RF efficacy was defined as the total ablation volume created within the total time during which valid RF current was generated.

The true RF efficacy of BRFE with 30 W at 60 s was significantly higher than that of BRFE with 20 W and 40 W during the preliminary experiment (p = 0.011). BRFE showed larger vertical and transverse diameters (DT1, DT2) than MRFE with a 0.5-cm active tip (all p values < 0.001, except 10 s). By contrast, MRFE with a 0.7-cm active tip created a larger DT1, DT2, volume, efficacy and true efficacy than BRFE (maximum p value = 0.011). The shape ratio of BRFE was significantly higher than that of MRFEs with 0.5-cm and 0.7-cm tips (all p < 0.001).

Application of BRFE with 30 W could achieve a median ablation volumes and efficacy between that of MRFEs with 0.5-cm and 0.7-cm active tips and created a more ellipsoid-shaped ablation zone.