中文摘要：

基于生物组织离散随机介质模型，对猪肝水浴加热过程中基于AR谱模型的超声频移进行了分析，通过建立AR模型来计算回波信号的功率谱并对研究结果进行了统计分析．结果表明：猪肝组织超声回波频率随温度的改变而变化．在20℃下猪肝组织超声回波最大频率平均为（3．55±0．09）MHz；在30℃下为（3．14±0．12）MHz；在40℃下为（2．87±0．11）MHz；在50℃下为（2．79±0．10）MHz；在60℃下为（2．72±0．08）MHz．随着温度的升高，频率降低．通过分析猪肝散射体在不同温度下的频率进行组织定征，以期达到监测微波消融过程中的消融区域，为临床监测微波消融提供一种可行的方法．

英文摘要：

In this paper, the ultrasonic frequency shift of in-vitro porcine liver with temperature change during the water bath heating process was analyzed and studied using the Autoregressive （AR） model, based on the discrete random medium model of biological tissues. The power spectrum density of the ultrasonic backscattered signal was computed by establishing the AR model. Statistical analysis was performed on the experimental results. The experimental results show that the mean frequencies of ultrasonic backscattered signals of the porcine liver tissues change with the temperature variation from 20 ℃ to 60℃. The mean frequency is （3.55±0.09） MHzat20℃, （3.14±0.12） MHzat30℃, （2.87 ±0.11） MHz at40℃, （2.79 ±0.10） MHz at 50 ℃, and （2.72±0.08） MHz at 60 ℃.These data suggest that the mean frequency decreases as the temperature increases. The mean frequency obtained using the AR model method may be used as a characteristic parameter for tissue characterization in the recognition of coagulation alterations during microwave hyperthermia, which may offer a potential pragmatic prospect for the practice of noninvasive monitoring of microwave hyperthermia.