Percutaneous Radiofrequency Ablation with a Multiple-Electrode Switching-Generator System

Abstract

To determine the feasibility and safety of treating 35 hepatic tumors with a multiple-electrode switching-generator radiofrequency (RF) ablation system. The authors performed a retrospective review of percutaneous RF ablation procedures in 35 hepatic tumors ranging in diameter from 0.9 to 3.8 cm and involving 22 patients. Tumors smaller than 2 cm were ablated with a single electrode, and larger tumors were ablated with two or three electrodes depending on tumor size and location of initial electrode placement. Electrodes were positioned 1-2 cm apart to create an intratumoral configuration that maximized index tumor coverage. Computed tomography or magnetic resonance imaging was performed within 24 hours of ablation. The ablation volume, maximum ablation size, and maximum tumor size were compared among the three electrode groups by using analysis of variance. If the global P value with analysis of variance was statistically significant (P<.05), post hoc testing for pairwise comparisons was performed by using the Bonferroni correction to adjust for multiple comparisons. Complications were defined according to the SIR reporting standards for image-guided tumor ablation. Ten tumors were treated with one electrode, 16 were treated with two electrodes, and nine were treated with three electrodes. The mean and median maximum sizes of the tumors ablated with one, two, and three electrodes were 1.2 and 1.1 cm, 2.7 and 2.8 cm, and 3.2 and 3.4 cm, respectively. The mean and median ablation volumes with two electrodes (40.9 and 31.9 cm3, respectively) and three electrodes (59.3 and 48.2 cm3, respectively) were significantly greater than that with one electrode (11.7 and 8.6 cm3, respectively; P<or=.0363 among comparisons). No major complications occurred that were directly attributable to the RF ablation procedure. Minor complications occurred in two patients (9%). Percutaneous RF ablation of hepatic tumors with a multiple-electrode switching-generator system is technically feasible, is safe, and generates ablation volumes greater than those seen with a single electrode.