Controlled Cryogenic Ablation Using Ultrasonic Sensing

摘要

The Cryoablation process is one of the methods for treating various tissue abnormities. Cryoablation devices are mostly minimally invasive and are used in open loop control, monitored by additional imaging devices. In this study, we monitor the growth of the ablated area by using a miniature ultrasonic transducer that is collocated with the tip of the cryogenic device. The 20 MHz ultrasonic sensor is capable of measuring the size of the ice sphere that is created in front of the needle. In addition to real time monitoring of the ablation process, the ultrasonic sensor will be able to determine the local thickness of the tissue prior to the treatment (thus enabling the setting of the power of the ablation treatment). The combined device will shorten the ablation treatment and will eliminate the need for additional ablation treatments or monitoring devices. The proof of concept was done in water, ultrasonic gel and muscle tissue. In the experiments we found that, in the frequency domain one can identify at 10-12 MHz the increase of the intensity of the returned echo in the ice and the decrease of the signal after the ice-tissue boundary. One can correlate the increase of the intensity with the growth of the ice sphere.