Calibration of a novel, laparoscopic, 12-mm, ultrasound, image-guided, high-intensity focused ultrasound probe for ablation of renal neoplasms.

OBJECTIVE: To calibrate a 12-mm high-intensity focused ultrasound (HIFU) probe to produce histologically verifiable complete tissue necrosis through thermal energy delivery while maintaining safety in ablation of porcine renal tissue. METHODS: The study was approved by the animal research committee at our institution. A HIFU probe on a fixed arm was introduced, and ablation was subsequently carried out robotically (under computer control) at 2 planned locations within each kidney at varying energy levels. After 4 days of survival, kidneys were retrieved and pathologic analysis of the lesions was carried out for necrotic volume. Planned volume was compared with pathologic necrotic volume. RESULTS: A series of optimizations were carried out as the experiment progressed. Near optimal ablation zone dimensions with complete cell death were achieved when the energy density was between 400 and 460 calories/cm(3). Pathologic analysis demonstrated the average ratio of necrotic zone volume to planned zone volume was 1.0 (standard deviation, 0.18) in the 7 lesions with energy density between 400 and 460 calories/cm(3). All animals survived the surgeries, and no device-related complications were identified during the study. No acute renal failure was identified in analysis of the blood work. CONCLUSION: A novel 12-mm laparoscopic HIFU probe was successfully calibrated for the ablation of porcine renal tissue. The safety profile of the Sonatherm probe was found to be excellent with no complications identified.

Comparison of measured renal tumor size versus R.E.N.A.L. nephrometry score in predicting patient outcomes after robot-assisted laparoscopic partial nephrectomy.

Partial nephrectomy (PN) is a technically challenging procedure, making selection of appropriate patients paramount to a successful operation. To identify patients at increased risk of an adverse outcome after PN, there are a number of scoring systems available. The nephrometry score was initially described in a series of laparoscopic and open partial and radical nephrectomies. We compare the association of the nephrometry score with perioperative outcomes in a population of robot-assisted partial nephrectomies. A total of 119 patients were retrospectively reviewed. Correlation and regressional analysis was performed. We identified the separate variables R, E, N, and L to have limited correlation and no predictive value to patient outcomes. Nephrometry score and grade were found to have stronger correlation and predictive value than the individual components of the R.E.N.A.L. nephrometry score. Size of tumor measured on a continuous scale was found to have the strongest correlation and predictive value to outcomes. Outcomes predicted included operative time, length of stay, warm ischemia time, and entry into the collecting system.

A validated mouse model for orthotopic bladder cancer using transurethral tumour inoculation and bioluminescence imaging.

OBJECTIVES: To describe a technique for transurethral tumour inoculation, bioluminescence imaging (BLI) and validation of this approach using ex vivo magnetic resonance imaging (MRI), as a reproducible and quantifiable model of orthotopic bladder cancer is required to enable preclinical pharmacological studies of intravesically administered anticancer agents and the use of BLI provides a sensitive method to monitor tumour growth over time. MATERIALS AND METHODS: Human KU-7 bladder tumour cells were transduced with a lentiviral construct to stably express the firefly luciferase gene. These cells were then inoculated in female nude mice by intravesical instillation. BLI was performed weekly and the mice were killed after 4 weeks. Ex vivo MRI and whole-mount step-sections were obtained to assess bladder tumour volume. RESULTS: KU-7 tumour cells were highly tumorigenic and were successfully inoculated in 96% of mice. After 4 weeks, all tumours were confined to the mucosa and submucosa (