J Korean Soc Radiol.  2012 Dec;67(6):425-431. 10.3348/jksr.2012.67.6.425.

Bipolar Radiofrequency Ablation Using Dual Internally Cooled Wet Electrodes: Experimental Study in Ex Vivo Bovine Liver

• Lee YJ
• Byun JY

• KMID: 2097977
• DOI: http://doi.org/10.3348/jksr.2012.67.6.425

Abstract

PURPOSE
To determine the optimized protocol for bipolar radiofrequency ablation (RFA), using dual internally cooled wet (ICW) electrodes in the ex vivo bovine liver.
MATERIALS AND METHODS
RFA was applied to the explanted bovine liver, using two 3 cm active tip electrodes with 3.5 cm spacing. A total of 25 ablation zones were created by five groups; group A: 70 W-20 minute (min), group B: 70 W-25 min, group C: 90 W-15 min, group D: 90 W-20 min, and group E: 90 W-25 min. We measured the total energy and size of ablation zones with a color of grey or pink. Statistical analysis was done using Kruskal Wallis test and Mann Whitney U-test.
RESULTS
The mean energy, mean volume of ablation zone with grey and pink color of groups A to E were 16.7, 23.9, 16.7, 21.8, 29.2 kcal, 25.7, 34.3, 29.5, 36.2, 45.2 cm3, and 60.0, 88.0, 71.5, 87.4, 104.5 cm3, respectively. Those were significantly different (p < 0.05). The volume of ablation zone of group E with grey color was larger than groups A, B and C (p < 0.05).
CONCLUSION
Bipolar RFA, using dual ICW electrodes, can produce a large ablation zone with the protocol of 90 W-25 min.

MeSH Terms

Electrodes
Liver

Figure

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  Fig. 1 Schematic diagram. A. Internal structure of internally cooled wet tip electrode with cooling and perfused flow (dotted arrows). B. Bipolar radiofrequency ablation system with single generator and two infusion pumps. Note.-RF = radiofrequency

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  Fig. 2 Measurement of the ablation with grey color. A. Dt is the long transverse diameter between the two electrodes and Dv (long dotted arrow) is the longitudinal diameter along the axis of electrodes. B. Ds (short dotted arrow) is the short transverse diameter of perpendicular plane at the middle between the two electrodes.

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  Fig. 3 Cut surfaces of coagulated necrosis along the axis of electrodes in the five groups. (A) group A; 70 W-20 min, (B) group B; 70 W-25 min, (C) group C; 90 W-15 min, (D) group D; 90 W-20 min, (E) group E; 90 W-25 min: Long transverse diameter between the two electrodes (arrows) of necrosis of 25 min groups (group B and E) is longer than that of group A and C. Longitudinal diameter along the axis of electrode of necrosis of group E is longer than that of group A, B, and C.

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  Fig. 4 Cut surfaces of coagulated necrosis, perpendicular plane at the middle between the two electrodes in the five groups. (A) group A; 70 W-20 min, (B) group B; 70 W-25 min, (C) group C; 90 W-15 min, (D) group D; 90 W-20 min, (E) group E; 90 W-25 min: Short transverse diameter of necrosis of 15 min duration groups (group A and C) is shorter than that of 20 and 25 min duration groups (group B, D, and E).

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