Features of Ultrasonic Radio Frequency Signal in Microwave Ablation Experiments

The main purpose of this paper was to validate whether the method using features of ultrasonic radio frequency signal (URFS) is effective for non-invasive monitoring in microwave ablation. A total of 15 fresh in vitro porcine livers were experimented. Features of amplitude integral, energy, sum of absolute value of difference (SAD) integral, time-shift and attenuation coefficient of URFS were extracted. Changing rules of these features and the relationships between time-shift, attenuation coefficient and tissue temperature were analyzed. Experimental results showed that maximums of amplitude integral, energy and SAD integral occur at the temperature within 50-60°C. In addition, there was a linear relationship between time-shift and tissue temperature within 60°C and the ultrasonic attenuation coefficient increased with the temperature rising. Therefore, features of URFS can reflect the change of tissue property and may be used in the non-invasive monitoring of microwave ablation in the future.