title: New ablation procedure for a radiofrequency liver tissue coagulation system using an expandable needle.
abstract: OBJECTIVE
  The stepwise hook extension technique for an expandable needle, which we reported previously, allowed roll-off in short time with low power. The aim of this study was to investigate experimentally the efficacy of a modified extension procedure.
  
  
  METHODS
  Three pigs underwent 10 radiofrequency ablation (RFA) procedures using the 10-hook electrode of LeVeen needle. The conventional technique was used in five RFA (group 1; the electrode was deployed in four steps to full extension), while the new technique was used in the other five RFA (group 2; the electrode was closed after the same three steps as group 1 and then fully extended).
  
  
  RESULTS
  The shape of the RFA-induced zone was cone-like or irregular in group 1 and oval-like in group 2. The diameter vertical to the shaft was larger in group 2 (37, range 33-42 mm) than in group 1 (23, range 20-29 mm). The median ablation time was longer in group 2 (10 min 13 s) than in group 1 (3 min 56 s). Although the required energy was higher in group 2 than in group 1, that per volume was comparable between the groups (median 0.9 vs. 1.4 kJ/mm(3)).
  
  
  CONCLUSIONS
  Our new procedure requires a longer session but produces larger necrosis of a uniform ellipsoid volume, making it potentially suitable for tumours more than 3 cm in diameter.
authors.affiliation: Department of Hepatology, Toranomon Hospital, Tokyo, Japan. ZXC00701@nifty.ne.jp
authors.forename: Miharu
authors.initials: M
authors.lastname: Hirakawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Ikeda
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kawamura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hosaka
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yatsuji
authors.forename: Hitomi
authors.initials: H
authors.lastname: Sezaki
authors.forename: Norio
authors.initials: N
authors.lastname: Akuta
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Suzuki
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Suzuki
authors.forename: Satoshi
authors.initials: S
authors.lastname: Saitoh
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Arase
authors.forename: Hiromitsu
authors.initials: H
authors.lastname: Kumada
mesh_terms: D000279:Administration, Cutaneous; D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000628:therapy*; D017115:Catheter Ablation / Q000295:instrumentation* / Q000379:methods*; D000431:Ethanol / Q000008:administration & dosage; D008099:Liver / Q000473:pathology; D009339:Needles; D034421:Sus scrofa
chemical_list: D000431:Ethanol