New ablation procedure for a radiofrequency liver tissue coagulation system using an expandable needle.
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.
Hirakawa
Miharu
M
Department of Hepatology, Toranomon Hospital, Tokyo, Japan. ZXC00701@nifty.ne.jp
Ikeda
Kenji
K
Kawamura
Yusuke
Y
Kobayashi
Masahiro
M
Hosaka
Tetsuya
T
Yatsuji
Hiromi
H
Sezaki
Hitomi
H
Akuta
Norio
N
Suzuki
Fumitaka
F
Suzuki
Yoshiyuki
Y
Saitoh
Satoshi
S
Arase
Yasuji
Y
Kumada
Hiromitsu
H
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
D000431:Ethanol