title: Ablation of renal tumors in a rabbit model with interstitial saline-augmented radiofrequency energy: preliminary report of a new technology.
abstract: OBJECTIVE
  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 ablative process in real time before, during, and after treatment.
  
  
  METHODS
  The VX-2 tumor was implanted beneath the renal capsule in 18 rabbit kidneys. Twelve days after implantation, 50 W of 500-kHz radiofrequency energy was delivered into the surgically externalized renal tumor and contralateral control kidney for 30 or 45-second treatment intervals using an interstitial saline-augmented radiofrequency probe (the virtual electrode). Localization of the tumor and response to treatment were imaged with gray-scale and power Doppler ultrasonography. The effect of radiofrequency and extent of the destructive process on benign and malignant renal tissue were evaluated histologically.
  
  
  RESULTS
  Mean tumor size was 1.3 x 0.7 cm. Both 30 and 45-second treatment intervals provided marked tissue/tumor ablation. Gross anatomic and histologic 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-second treatment), with clear demarcation of the surrounding parenchyma. Conventional gray-scale sonography allowed visualization of the ablative process, and power Doppler ultrasound demonstrated changes in the vascular pattern of the tumor both before and after ablation. No immediate treatment-related complications were observed.
  
  
  CONCLUSIONS
  These preliminary studies in a rabbit model demonstrate the feasibility of using the interstitial saline-augmented electrode to ablate small renal tumors and the ability to simultaneously visualize the ablative process using real-time ultrasonography. This technology may have the potential to treat small renal tumors in a minimally invasive manner in the clinical setting.
authors: Department of Urology, The Johns Hopkins Medical Institutions, Baltimore, Maryland, USA.
authors: T J
authors: TJ
authors: Polascik
authors: U
authors: U
authors: Hamper
authors: B R
authors: BR
authors: Lee
authors: Y
authors: Y
authors: Dai
authors: J
authors: J
authors: Hilton
authors: C A
authors: CA
authors: Magee
authors: J K
authors: JK
authors: Crone
authors: M J
authors: MJ
authors: Shue
authors: M
authors: M
authors: Ferrell
authors: V
authors: V
authors: Trapanotto
authors: M
authors: M
authors: Adiletta
authors: A W
authors: AW
authors: Partin
mesh_terms: D000818:Animals; D004598:Electrosurgery; D005069:Evaluation Studies as Topic; D007680:Kidney Neoplasms / Q000601:surgery*; D011817:Rabbits; D012965:Sodium Chloride
chemical_list: D012965:Sodium Chloride