title: Microwave ablation versus radiofrequency ablation in the kidney: high-power triaxial antennas create larger ablation zones than similarly sized internally cooled electrodes.
abstract: OBJECTIVE
  To determine whether microwave ablation with high-power triaxial antennas creates significantly larger ablation zones than radiofrequency (RF) ablation with similarly sized internally cooled electrodes.
  
  
  METHODS
  Twenty-eight 12-minute ablations were performed in an in vivo porcine kidney model. RF ablations were performed with a 200-W pulsed generator and either a single 17-gauge cooled electrode (n = 9) or three switched electrodes spaced 1.5 cm apart (n = 7). Microwave ablations were performed with one (n = 7), two (n = 3), or three (n = 2) 17-gauge triaxial antennas to deliver 90 W continuous power per antenna. Multiple antennas were powered simultaneously. Temperatures 1 cm from the applicator were measured during two RF and microwave ablations each. Animals were euthanized after ablation and ablation zone diameter, cross-sectional area, and circularity were measured. Comparisons between groups were performed with use of a mixed-effects model with P values less than .05 indicating statistical significance.
  
  
  RESULTS
  No adverse events occurred during the procedures. Three-electrode RF (mean area, 14.7 cm(2)) and single-antenna microwave (mean area, 10.9 cm(2)) ablation zones were significantly larger than single-electrode RF zones (mean area, 5.6 cm(2); P = .001 and P = .0355, respectively). No significant differences were detected between single-antenna microwave and multiple-electrode RF. Ablation zone circularity was similar across groups (P > .05). Tissue temperatures were higher during microwave ablation (maximum temperature of 123 degrees C vs 100 degrees C for RF).
  
  
  CONCLUSIONS
  Microwave ablation with high-power triaxial antennas created larger ablation zones in normal porcine kidneys than RF ablation with similarly sized applicators.
authors.affiliation: Department of Radiology, University of Wisconsin, 600 Highland Avenue, Madison, WI 53792, USA. plaeseke@gmail.com
authors.forename: Paul F
authors.initials: PF
authors.lastname: Laeseke
authors.forename: Fred T
authors.initials: FT
authors.lastname: Lee
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Sampson
authors.forename: Daniel W
authors.initials: DW
authors.lastname: van der Weide
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Brace
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods; D003080:Cold Temperature; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D007668:Kidney / Q000473:pathology / Q000601:surgery*; D008872:Microwaves / Q000627:therapeutic use*; D009392:Nephrectomy / Q000295:instrumentation* / Q000379:methods; D013552:Swine