Experimental Study for Electrovaporization of Renal Cell Carcinoma Using a New Shape Memory Alloy Probe

Objectives

To develop a new shape memory alloy probe for percutaneous treatment of renal cell carcinoma (RCC) by electrovaporization, and investigate its efficacy and safety in experimental models.

Methods

The shape memory alloy electrode can be manipulated to any shape at room temperature and regains its original shape at ≥65°C. By adding a high-frequency electric current to the probe, the electrodes quickly regain their original shape and vaporize tissues into a spherical defect. The performance of this probe was tested using agar, dog kidney, and rat RCC models. The treatment effect was evaluated by magnetic resonance imaging and histologic examination.

Results

In the agar model, the electrovaporization inside the spherical electrode was successfully achieved in several seconds, with all power outputs tested. The area of ≥60°C extended about 5 mm beyond the periphery of the vaporized part and corresponded with the histologic findings on the dog kidney that an irreversible heat denaturation occurred to the same extent. The study on the RCC model also confirmed that about 5-mm extent of heat denaturation was seen in the muscular tissue adjacent to the tumor. In the study using the RCC model, some remaining tissues close to the tumor were observed after vaporization. However, dynamic magnetic resonance imaging demonstrated no enhancement in this area and no viable tumor cells were documented by histologic examination.

Conclusions

This novel tissue ablation system has potential as a viable option for percutaneous treatment of renal tumors.