Radio-frequency tumor ablation: internally cooled electrode versus saline-enhanced technique in an aggressive rabbit tumor model.
OBJECTIVE
To compare two methods of radio-frequency (RF) ablation, saline enhancement technique and internally cooled electrodes, for the treatment of small breast cancers in an animal model--highly aggressive VX2 rabbit tumors surrounded by adipose tissue.


METHODS
Twenty-seven tumors were implanted into retroperitoneal fat of 14 New Zealand White rabbits. RF ablation was performed with ultrasonographic (US) guidance after tumors had grown to 15 mm. Fourteen tumors in seven animals were treated with internally cooled electrodes (30-mm-tip single electrode, 60 W, 10 min); 13 tumors in seven animals, with saline enhancement (0.5 mL/min of saline, 25-mm tip, 30 W, 10 min). Autopsy and histopathologic assessment were performed 3 weeks after therapy.


RESULTS
Real-time US of RF ablation was not possible with either method because of obscuration by the increasing hyperechogenicity of the tumor and the surrounding adipose tissue. Equivalent efficacy was demonstrated with the two methods. Significantly greater complications were observed with the saline technique: Free retroperitoneal fluid was detected in one of seven animals with internally cooled electrodes and in all seven animals with saline enhancement (P <.01). Damage to remote structures such as the kidney, spine muscle, and skin was observed at autopsy in one of seven animals with internally cooled technique versus five of seven with saline enhancement (P <.01).


CONCLUSIONS
Given a lower complication rate and similar treatment efficacy in an animal tumor model, internally cooled RF electrode may be advantageous to adjuvant saline infusion for the minimally invasive treatment of breast tumors.
Boehm
Thomas
T
Department of Diagnostic Radiology, Universitätsspital Zürich, Rämistrasse 100, CH-8091 Zürich, Switzerland. thomas_boehm@gmx.de
Malich
Ansgar
A
Goldberg
S Nahum
SN
Reichenbach
Jürgen R
JR
Hilger
Ingrid
I
Hauff
Peter
P
Reinhardt
Michael
M
Fleck
Marlies
M
Kaiser
Werner A
WA
D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D004566:Electrodes; D005260:Female; D008325:Mammary Neoplasms, Experimental / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D009368:Neoplasm Transplantation; D011817:Rabbits; D012965:Sodium Chloride / Q000008:administration & dosage*; D014407:Tumor Cells, Cultured; D018084:Ultrasonography, Interventional
D012965:Sodium Chloride