V5-12: Calibration of Novel 12mm Laparoscopic High Intensity Ultrasound Probe for Ablation of Renal Neoplasms
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Introductions and ObjectivesHigh intensity focused ultrasound (HIFU) has been described for ablative therapy in a range of organs. Previously, HIFU probes were only available in 18 mm diameter making laparoscopic use for renal ablation difficult. We developed and optimized a protocol for a novel 12 mm HIFU probe for treatment of renal masses in a porcine model. The objectives of the protocol were to demonstrate efficacy of the probe in ablation of renal tissue/ tumors, and to demonstrate safety of the probe in live surgery.
Methods
This study was conducted at the LARC animal facility at Indiana University after approval of the protocol by the animal research committee. We carried out laparoscopic dissection to expose each of the 16 individual renal units. We then introduced the HIFU probe on a fixed arm, and ablation was subsequently carried out at two planned locations within each kidney. After four days of survival, kidneys were retrieved and pathologic analysis of the lesions was carried out for necrotic volume (NV). Planned volume (PV) was compared to the determined pathologic NV. Pre-operative and post-operative bloodwork was collected from all animals.
Results
A series of optimizations were carried out as the experiment progressed and we gained technical insight with each animal. Optimization of energy delivery settings was required in the form of probe speed and spacing to attain proper cell death within the ablation margins as assessed by pathology._x000D_ _x000D_ After the series of modifications, we were able to achieve near optimal lesions in the last two animals. The energy density was noted to be 400-460 C/cm3 in these lesions. Pathologic analysis demonstrated necrotic zones (NV) with similar volumes to targeted zones (PV). The NV/PV was near optimal at a value of 1.0 (std dev 0.18) across these 8 lesions. All animals survived the surgeries and no complications were identified during the study. No acute renal failure was identified in analysis of the bloodwork.
Conclusions
We successfully demonstrated use of a novel 12mm laparoscopic HIFU probe to consistently ablate porcine renal tissue. A value of NV/PV near the ideal ratio of 1.0 was achieved. The safety profile of the SonaTherm probe was found to be excellent with no complications identified. Further studies are required to characterize the probe’s efficacy in ablation of small renal masses in humans.
Funding: SonaCare Medical LLC