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

Figures & data

Figure 1. Photographs of thyroid-dedicated bipolar electrode in this study. (A) Structure of bipolar electrode that contains modified internal cooling system and the tip containing a pair of electrodes on the same needle. (B) A magnified photograph of the electrode tip that has a ratio of 5.5:2:8 for cathode, connecting portion with insulation, and anode, respectively.

Figure 2. The cross-sectional views of each time–power combination in the experiment for the bipolar electrode. Ablation zone of corresponding powers (row) for corresponding times (column).

Table 1. Preliminary experiment data of the bipolar electrode.

Ablation power	Variables
	DV (cm)	DT1 (cm)	DT2 (cm)	Volume (mL)	True efficacy (mL/s)
20 W
60 s	1.25 ± 0.16	0.70 ± 0.07	0.80 ± 0.07	0.37 ± 0.09	0.010 ± 0.002*
120 s	1.35 ± 0.12	0.79 ± 0.07	0.89 ± 0.06	0.5 ± 0.11	0.008 ± 0.002
30 W
60 s	1.28 ± 0.09	0.71 ± 0.06	0.76 ± 0.06	0.37 ± 0.06	0.014 ± 0.002
120 s	1.31 ± 0.12	0.81 ± 0.07	0.88 ± 0.04	0.49 ± 0.09	0.010 ± 0.001
40 W
60 s	1.22 ± 0.10	0.69 ± 0.06	0.75 ± 0.06	0.33 ± 0.06	0.013 ± 0.002
120 s	1.30 ± 0.10	0.76 ± 0.08	0.82 ± 0.09	0.43 ± 0.11	0.010 ± 0.002

True efficacy: ablation efficacy in a true RF time; DV: vertical diameter; DT1: transverse diameter 1; DT2: transverse diameter 2.

Data are means ± standard deviations.

* p value < 0.0167 after Bonferroni’s correction was considered as statistically significant.

Figure 3. The cross-sectional views of each time–electrode combinations in comparison experiments between bipolar and monopolar electrodes. Ablation zone of corresponding BRFE and each MRFE tips (0.5, 0.7 and 1 cm) (row) for corresponding time (column). BRFE: bipolar RF electrode; MRFE: monopolar RF electrode.

Table 2. Comparison data of the bipolar and monopolar electrodes.

Electrodes	Variables
	True efficacy (mL/s)	Shape ratio
BRFE
10 s	0.010 ± 0.001	2.43 ± 0.17
30 s	0.014 ± 0.003	1.79 ± 0.23
60 s	0.014 ± 0.002	1.74 ± 0.17
120 s	0.010 ± 0.001	1.56 ± 0.12
MRFE 0.5 cm
10 s	0.008 ± 0.003*	1.5 ± 0.2*
30 s	0.007 ± 0.001	1.21 ± 0.14*
60 s	0.008 ± 0.001	1.1 ± 0.1*
120 s	0.005 ± 0.001	1.1 ± 0.11*
MRFE 0.7 cm
10 s	0.013 ± 0.001*	1.85 ± 0.15*
30 s	0.016 ± 0.001*	1.28 ± 0.06*
60 s	0.016 ± 0.002*	1.16 ± 0.09*
120 s	0.010 ± 0.002*	1.04 ± 0.1*
MRFE 1.0 cm
10 s	0.011 ± 0.001	3.54 ± 0.47*
30 s	0.026 ± 0.003*	1.81 ± 0.14
60 s	0.029 ± 0.002*	1.4 ± 0.11*
120 s	0.024 ± 0.003*	1.2 ± 0.05*

True efficacy: ablation efficacy in a true RF time; BRFE: bipolar RF electrode; MRFE: monopolar RF electrode.

Data are means ± standard deviations.

* p values of comparison between BRFE and each MRFE groups, p value of <0.0167 after Bonferroni’s correction was considered as statistically significant.