Radiofrequency ablation of subcapsular lesions with internally cooled perfusion electrode: ex vivo study.

Purpose: To compare the ex vivo efficiency of an internally cooled perfusion (ICP) electrode and an internally cooled (IC) electrode for radiofrequency ablation (RFA) of subscapular lesions.Material and methods: Using 200 W generator and ICP electrode (group A, n = 10) or 15 gauge or 17 gauge IC electrode (group B, n = 10 and group C, n = 10), RFA was applied to the bovine liver for 12 min. Each electrode was inserted at a 3 cm depth into the liver block, and the proximal end of the active exposure portion of each electrode was located at a capsule of the liver block. During RFA, normal saline was pumped through the side hole of the ICP electrode into the tissue at an injection rate of 0.5 mL/min.Results: The ICP electrode achieved larger capsular ablative area and ablative volume than the IC electrode: 7.29 ± 1.59 cm2 and 44.56 ± 10.08 cm3 in group A; 4.36 ± 1.29cm2 and 30.15 ± 5.97 cm3 in group B; and 3.57 ± 0.99cm2 and 24.52 ± 4.21 cm3 in group C (p < .05), respectively. Mean impedance of ICP RFA was lower than IC RFA: 41.5 ± 3.75Ω in group A; 52.4 ± 5.64Ω in group B; and 58.1 ± 10.98Ω in group C (p < .05).Conclusion: RFA using the ICP electrode more efficiently created a larger capsular ablative area and ablative volume of ablation than IC RFA for subcapsular lesions. The results were obtained in an ex vivo liver model without tumor simulation inside.