title: Microwave ablation using 915-MHz and 2.45-GHz systems: what are the differences?
abstract: OBJECTIVE
  This study was conducted to evaluate differences between 915-MHz and 2.45-GHz microwave ablation (MWA) systems in the ablation of hepatic tumours.
  
  
  METHODS
  A retrospective analysis of patients undergoing hepatic tumour MWA utilizing two different systems over a 10-month period was carried out.
  
  
  RESULTS
  Data for a total of 48 patients with a mean age of 58 ± 1.24 years were analysed. A total of 124 tumours were ablated; 72 tumours were ablated with a 915-MHz system and 52 with a 2.45-GHz system. Mean tumour diameters were 1.7 ± 0.1 cm in the 915-MHz group and 2.5 ± 0.2 cm in the 2.45-GHz group (P < 0.01). Mean ablation time per burn was 8.1 ± 0.3 min in the 915-MHz group and 4.0 ± 0.1 min in the 2.45-GHz group (P < 0.01). The mean number of burns per lesion was 2.0 ± 0.1 in the 915-MHz group and 1.7 ± 0.1 in the 2.45-GHz group (P < 0.05). The mean ablation time per lesion was 9.7 ± 0.7 min in the 915-MHz group, and 6.6 ± 0.6 min in the 2.45-GHz group (P < 0.01). The 2.45-GHz system demonstrated a better correlation between ablation time and tumour size (r(2) = 0.6222) than the 915-MHz system; (r(2) = 0.0696). Mean total energy applied per lesion, and energy applied per cm, were greater with the 915-MHz system (P < 0.05 and P < 0.01, respectively). Total energy applied per lesion was similarly correlated for the 2.45-GHz (r(2) = 0.6263) and 915-MHz (r(2) = 0.7012) systems. Mean total energy applied per cm/min was greater with the 2.45-GHz system (P < 0.05).
  
  
  CONCLUSIONS
  Both 915-MHz and 2.45-GHz MWA systems achieve reproducible hepatic tumour ablation. The 2.45-GHz system achieves equivalent, but more predictable and faster ablations using a single antenna system.
authors.affiliation: Section of Hepatobiliary and Pancreas Surgery, Carolinas Medical Center, Charlotte, NC, USA.
authors.forename: Kerri A
authors.initials: KA
authors.lastname: Simo
authors.forename: Victor B
authors.initials: VB
authors.lastname: Tsirline
authors.forename: David
authors.initials: D
authors.lastname: Sindram
authors.forename: Matthew T
authors.initials: MT
authors.lastname: McMillan
authors.forename: Kyle J
authors.initials: KJ
authors.lastname: Thompson
authors.forename: Ryan Z
authors.initials: RZ
authors.lastname: Swan
authors.forename: Iain H
authors.initials: IH
authors.lastname: McKillop
authors.forename: John B
authors.initials: JB
authors.lastname: Martinie
authors.forename: David A
authors.initials: DA
authors.lastname: Iannitti
mesh_terms: D055011:Ablation Techniques / Q000009:adverse effects / Q000295:instrumentation*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004867:Equipment Design; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology / Q000601:surgery*; D008297:Male; D008872:Microwaves / Q000009:adverse effects / Q000627:therapeutic use*; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome