title: Optimal ablation volumes are achieved at submaximal power settings in a 2.45-GHz microwave ablation system.
abstract: BACKGROUND
  Local ablative therapies, including microwave ablation (MWA), are common treatment modalities for in situ tumor destruction. Currently, 2.45-GHz ablation systems are gaining prominence because of the shorter application times required. The aims of this study were to determine optimal power and time to ablation volume (AbV) ratios for a new 1.8-mm-2.45-GHz antenna using ex vivo tissue models.
  
  
  METHODS
  The 1.8-mm-2.45-GHz Accu2i MWA system was employed to perform ablations in bovine liver, porcine muscle, and porcine kidney ex vivo. Whole tissues were prewarmed (35°C) and multiple ablations performed at power settings of 60 to 180 W for 2- to 6-minute time intervals. Postablation, tissues were dissected, AbVs calculated, and correlations to power and time settings made.
  
  
  RESULTS
  Significant increases in AbV were measured between each of the time points for a constant power setting in all 3 tissues. Increasing power settings led to significant increases in AbV at power settings ≤140 W. However, no significant increase in AbV was obtained at power settings >140 W.
  
  
  CONCLUSIONS
  Optimal efficiency for MWA using a new 1.8-mm-2.45-GHz system is achieved at settings of ≤140 W for 6 minutes in a range of ex vivo tissue and no additional benefit occurs by increasing the power setting to 180 W in these tissues.
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: David J
authors.initials: DJ
authors.lastname: Niemeyer
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Kerri A
authors.initials: KA
authors.lastname: Simo
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Matthew T
authors.initials: MT
authors.lastname: McMillan
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Ramanathan M
authors.initials: RM
authors.lastname: Seshadri
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Erin M
authors.initials: EM
authors.lastname: Hanna
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Jacob H
authors.initials: JH
authors.lastname: Swet
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Ryan Z
authors.initials: RZ
authors.lastname: Swan
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: David
authors.initials: D
authors.lastname: Sindram
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: John B
authors.initials: JB
authors.lastname: Martinie
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA iain.mckillop@carolinashealthcare.org.
authors.forename: Iain H
authors.initials: IH
authors.lastname: McKillop
authors.affiliation: Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Iannitti
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000379:methods*; D002417:Cattle; D007668:Kidney / Q000601:surgery; D008099:Liver / Q000601:surgery; D008872:Microwaves / Q000627:therapeutic use*; D018482:Muscle, Skeletal / Q000601:surgery; D025321:Surgery, Computer-Assisted; D013552:Swine; D013997:Time Factors
keywords: image guided surgery; liver; surgical oncology