title: Radiofrequency ablation with a high-power generator: device efficacy in an in vivo porcine liver model.
abstract: OBJECTIVE
  The purpose of this study was to test the feasibility and efficacy of using a high-power generator with nondeployable electrodes to create large zones of coagulation in an in vivo porcine liver model.
  
  
  METHODS
  With approval from our institution's research animal care and use committee, 12 female swine (mean weight = 55 kg) were anesthetized and received RF ablation at laparotomy. Twenty-nine ablations were performed in four groups using: (i) a conventional 200-W generator and cluster electrode (n = 4), or an experimental prototype 250-W generator and (ii) a single, 17-gauge electrode (n = 9), (iii) a cluster electrode (n = 8) or (iv) three electrodes spaced 2.0 cm apart in a triangular configuration (n = 8). In the three-electrode group, power was applied by switching between electrodes using a prototype switching device. All electrodes were internally cooled. Ablation zone size, shape and generator data from each group were compared using a mixed-linear model with animals modeled as random effects.
  
  
  RESULTS
  The high-power generator was able to increase significantly the zone of coagulation. Mean (+/-SD) ablation diameter was largest in the switched group (4.31 +/- 0.7 cm) followed by the cluster (3.98 +/- 0.5 cm) and single-electrode (3.26 +/- 0.5 cm) groups. Mean diameter in the high-power single-electrode group was no different than the low-power cluster group (3.25 +/- 0.4 cm, p = 0.98). Circularity measures were high (>0.75) in all groups.
  
  
  CONCLUSIONS
  Coupling a high-power generator and switching device is feasible. At higher powers, the switching device creates larger zones of ablation than cluster or single electrodes. Single-electrode ablations created with the prototype high-power generator were equivalent to those produced with the cluster electrode at conventional lower powers.
authors.affiliation: Department of Radiology, Madison, WI 53792, USA. clbrace@wisc.edu
authors.forename: C L
authors.initials: CL
authors.lastname: Brace
authors.forename: P F
authors.initials: PF
authors.lastname: Laeseke
authors.forename: L A
authors.initials: LA
authors.lastname: Sampson
authors.forename: T M
authors.initials: TM
authors.lastname: Frey
authors.forename: R
authors.initials: R
authors.lastname: Mukherjee
authors.forename: F T
authors.initials: FT
authors.lastname: Lee
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D005240:Feasibility Studies; D005260:Female; D006358:Hot Temperature; D006979:Hyperthermia, Induced / Q000379:methods; D066298:In Vitro Techniques; D008099:Liver / Q000473:pathology / Q000528:radiation effects*; D023421:Models, Animal; D013552:Swine