title: Development of a highly efficient implanted thermal ablation device: in vivo experiment in rat liver.
abstract: OBJECTIVE
  To evaluate an implanted thermal ablation device that can be heated with high efficiency using a resonant circuit as the implant.
  
  
  METHODS
  16 rats were used. The implants, adjusted at a resonance frequency of 4 MHz, were fixed on the surface of the liver of rats under laparotomy. In 14 of 16 rats, an alternating magnetic field (AMF) was applied for 6 min with an output of 300 W from outside the body using a ferrite core applicator. The implant temperature during AMF exposure was measured. The 14 rats were divided into 5 groups, depending on time from AMF application until they were sacrificed (1 h, 1 day, 3 days, 7 days and 1 month after application). Two rats not exposed to AMF were used as controls. Livers were removed and evaluated; the cross-sectional area and width of the ablated region were measured.
  
  
  RESULTS
  During AMF exposure, the implant temperature rose to 127.8±39.3 °C (mean±standard deviation). The cross-sectional area of the ablated region was largest after 1 day and tended to decrease with time. The widths of the ablated region were 4.87±0.22 mm, 4.15±0.36 mm, 3.67±0.58 mm and 3.24±0.16 mm in the 1 day, 3 day, 7 day and 1 month groups, respectively. No significant differences (p<0.05) were seen in either cross-sectional area or width of the ablated region.
  
  
  CONCLUSIONS
  Sufficient heat for ablation was obtained in vivo using a newly developed implanted thermal ablation device. This device may be a new option for thermal ablation therapy.
authors.affiliation: Department of Radiology, Osaka City University Graduate School of Medicine, Osaka, Japan. chu_3@i.707.to
authors.forename: H
authors.initials: H
authors.lastname: Matsui
authors.forename: M
authors.initials: M
authors.lastname: Hamuro
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: H
authors.initials: H
authors.lastname: Kayahara
authors.forename: K
authors.initials: K
authors.lastname: Murano
authors.forename: Y
authors.initials: Y
authors.lastname: Kotsuka
authors.forename: Y
authors.initials: Y
authors.lastname: Miki
mesh_terms: D000818:Animals; D004598:Electrosurgery / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006498:Hepatectomy / Q000295:instrumentation*; D006979:Hyperthermia, Induced / Q000295:instrumentation*; D008099:Liver / Q000473:pathology* / Q000601:surgery*; D008280:Magnetics / Q000295:instrumentation*; D008297:Male; D010865:Pilot Projects; D051381:Rats