Percutaneous US-guided radiofrequency ablation with perfused needle applicators: improved survival with the VX2 tumor model in rabbits.
OBJECTIVE
To evaluate survival, metastases, tumor necrosis, and prediction of local recurrence after percutaneous ultrasonographically (US) guided radiofrequency (RF) thermal ablation with electrodes perfused continuously with isotonic saline.


METHODS
VX2 liver tumors were implanted in 31 rabbits according to a standardized protocol. After 21 days, 16 animals were treated percutaneously with RF ablation. Four animals died of complications related to anesthesia, and 12 animals were evaluated. All animals were followed for 110 days and monitored with computed tomography (CT) and US at 1, 7, and 30 days. A control group of 15 animals did not receive treatment. Autopsy was performed at the end of scheduled follow-up or immediately after death. For survival analysis, the Kaplan-Meier method was used; for nominal data, the Fisher exact test was used.


RESULTS
In comparison to controls, animals in the treatment group showed significantly prolonged survival (P <.001). Eight of 12 animals (67%) treated with RF ablation survived to 110 days, while none of the controls did so. Metastases developed in all controls (100%) and in eight of 12 treated animals (67%) (P =.001). In comparison with controls, animals that developed metastases despite treatment also showed significantly prolonged survival (P =.02). Local recurrence was observed in three of 12 animals (25%) in the treatment group. CT and US performed 1 week after treatment did not allow prediction of local recurrence.


CONCLUSIONS
RF ablation of liver tumors with perfused needle applicators prolongs survival in the VX2 rabbit liver tumor model, regardless of whether complete remission is achieved. In comparison with controls, RF ablation results in a lower frequency of metastases.
Hänsler
Johannes
J
Department of Medicine I, Institute of Pathology, and Institute of Diagnostic Radiology, Friedrich-Alexander-University of Erlangen-Nuremberg, Ulmenweg 18, 91054 Erlangen, Germany. johannes.haensler@med1.med.uni-erlangen.de
Neureiter
Daniel
D
Wasserburger
Milan
M
Janka
Rolf
R
Bernatik
Thomas
T
Schneider
Thomas
T
Müller
Wolfgang
W
Frieser
Markus
M
Schaber
Stefan
S
Becker
Dirk
D
Hahn
Eckhart G
EG
Strobel
Deike
D
D000818:Animals; D017115:Catheter Ablation / Q000295:instrumentation / Q000379:methods*; D004195:Disease Models, Animal; D008114:Liver Neoplasms, Experimental / Q000000981:diagnostic imaging / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D009339:Needles; D011817:Rabbits; D015996:Survival Rate; D014463:Ultrasonography