title: Multiple-electrode radiofrequency ablations using Octopus® electrodes in an in vivo porcine liver model.
abstract: OBJECTIVE
  The objective of this study was to determine the in vivo efficacy of radiofrequency ablation (RFA) in porcine liver using Octopus® electrodes for creating a large coagulation compared with RFA using clustered electrodes.
  
  
  METHODS
  A total of 39 coagulations were created using a 200-W generator and clustered electrodes or Octopus electrodes during laparotomy in 19 pigs. Radiofrequency was applied to the livers using four protocols: (1) Group A-1, monopolar mode using a clustered electrode (n=11); (2) Group A-2, monopolar mode using an Octopus electrode (n=11); (3) Group B-1, consecutive monopolar mode using three, clustered electrodes (n=8); and (4) Group B-2, switching monopolar mode using two Octopus electrodes (n=9). The energy efficiency, shape, diameters (D) and volume (V) of the coagulation volume were compared in each of the two groups.
  
  
  RESULTS
  The mean maximum D and V of the coagulations in Group A-2 (4.7 cm and 33.1 cm(3), respectively) were significantly larger than those in Group A-1 (4.1 cm and 20.3 cm(3), respectively) (p<0.05). Furthermore, the mean minimum D, maximum D and V of the coagulations in Group B-2 were significantly larger than those in Group B-1, i.e. 5.3 vs 4.0 cm, 6.6 vs 4.9 cm and 66.9 vs 30.2 cm(3), respectively (p<0.05). The energy efficiencies were also significantly higher in Groups A-2 and B-2 than in Groups A-1 and B-1 (p<0.05).
  
  
  CONCLUSIONS
  The Octopus electrodes were more efficient for creating a large ablation zone than clustered electrodes, and the efficacy of RFA with Octopus electrodes can be amplified in the switching monopolar mode.
authors.affiliation: Department of Radiology, Seoul NationalUniversity College of Medicine, Seoul, Republic of Korea.
authors.forename: E S
authors.initials: ES
authors.lastname: Lee
authors.forename: J M
authors.initials: JM
authors.lastname: Lee
authors.forename: W S
authors.initials: WS
authors.lastname: Kim
authors.forename: S H
authors.initials: SH
authors.lastname: Choi
authors.forename: I
authors.initials: I
authors.lastname: Joo
authors.forename: M
authors.initials: M
authors.lastname: Kim
authors.forename: D H
authors.initials: DH
authors.lastname: Yoo
authors.forename: R-E
authors.initials: RE
authors.lastname: Yoo
authors.forename: J K
authors.initials: JK
authors.lastname: Han
authors.forename: B I
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006498:Hepatectomy / Q000295:instrumentation*; D008099:Liver / Q000473:pathology* / Q000601:surgery*; D008297:Male; D013552:Swine