超声激发声信号幅值实时监测HIFU焦域组织损伤*

聚焦超声消融肿瘤过程中的损伤实时监测是临床治疗面临的一个关键难题，双频聚焦超声不仅能提高治疗效率，且能在共焦区域激发出声信号，该声信号的幅值、频率等信息与焦域组织的机械和声学特性紧密相关。本文构建了一种双频聚焦超声治疗及组织损伤实时监测系统。该系统在聚焦超声辐照离体组织过程中，通过外部水听器接收双频激发的组织声发射信号，并通过上位机进行高速数据采集、数字滤波、时频处理等，分析声发射信号幅值与离体组织损伤之间的变化规律。实验研究结果表明：随着焦域组织损伤的形成，其弹性等声学特征发生改变，导致声发射信号幅值逐渐降低，表明声发射信号幅值的变化可较好地反映靶组织声学特征和结构的变化，从而实现聚焦超声治疗中靶组织损伤的实时监测。本文提出的监测方案相比传统超声影像监控更灵敏，有望为聚焦超声临床治疗中的组织损伤监控提供一种新的实时监测方案和手段。

Real time monitoring of tissue damage in HIFU focal region by ultrasonic excitation acoustic signal amplitude

Real time damage monitoring in the process of focused ultrasound ablation is a key problem in clinical treatment. Dual frequency focused ultrasound can not only improve the treatment efficiency, but also stimulate the acoustic signal in the confocal region. The amplitude and frequency of the acoustic signal are closely related to the mechanical and acoustic characteristics of the focal region tissue. In this paper, a dual frequency focused ultrasound treatment and tissue damage real-time monitoring system is constructed. During the process of focused ultrasound irradiating the tissue in vitro, the system receives the tissue acoustic emission signal excited by dual frequency through the external hydrophone, and carries out high-speed data acquisition, digital filtering, time-frequency processing and so on through the upper computer to analyze the change law between the amplitude of acoustic emission signal and the tissue damage in vitro. The experimental results show that: with the formation of focal area tissue damage, its elastic and other acoustic characteristics change, resulting in the gradual decrease of acoustic emission signal amplitude, indicating that the change of acoustic emission signal amplitude can better reflect the changes of acoustic characteristics and structure of target tissue, so as to realize the real-time monitoring of target tissue damage in focused ultrasound therapy. The monitoring scheme proposed in this paper is more sensitive than traditional ultrasound image monitoring, which is expected to provide a new real-time monitoring scheme and means for tissue damage monitoring in focused ultrasound clinical treatment.