Tj. Polascik et al., Ablation of renal tumors in a rabbit model with interstitial saline-augmented radiofrequency energy: Preliminary report of a new technology, UROLOGY, 53(3), 1999, pp. 465-470
Objectives. To evaluate the efficacy of interstitial saline radiofrequency
energy for reproducibly ablating nonmalignant (control) and malignant (the
VX-2 tumor) renal tissue in a rabbit model, and to determine the ability of
conventional gray-scale and power sonography to image the tumor and ablati
ve process in real time before, during, and after treatment.
Methods. The VX-2 tumor was implanted beneath the renal capsule in 18 rabbi
t kidneys. Twelve days after implantation, 50 W of 500-kHz radiofrequency e
nergy was delivered into the surgically externalized renal tumor and contra
lateral control kidney for 30 or 45-second treatment intervals using an int
erstitial saline-augmented radiofrequency probe (the virtual electrode). Lo
calization of the tumor and response to treatment were imaged with gray-sca
le and power Doppler ultrasonography. The effect of radiofrequency and exte
nt of the destructive process on benign and malignant renal tissue were eva
luated histologically.
Results. Mean tumor size was 1.3 x 0.7 cm. Both 30 and 45-second treatment
intervals provided marked tissue/tumor ablation. Cross anatomic and histolo
gic analysis showed time-dependent ablated lesions averaging 1.4 +/- 0.3 x
1.0 +/- 0.3 cm (30-second treatment) and 1.8 +/- 0.4 x 1.5 +/- 0.3 cm (45-s
econd treatment), with clear demarcation of the surrounding parenchyma. Con
ventional gray-scale sonography allowed visualization of the ablative proce
ss, and power Doppler ultrasound demonstrated changes in the vascular patte
rn of the tumor both before and after ablation. No immediate treatment-rela
ted complications were observed.
Conclusions. These preliminary studies in a rabbit model demonstrate the fe
asibility of using the interstitial saline-augmented electrode to ablate sm
all renal tumors and the ability to simultaneously visualize the ablative p
rocess using real-time ultrasonography. This technology may have the potent
ial to treat small renal tumors in a minimally invasive manner in the clini
cal setting. (C) 1999, Elsevier Science Inc. All rights reserved.