高强度聚焦超声辐照靶区回声强度与温度的相关性实验研究

Experiment study on relationship between temperature and echo enhancement of HIFU target region

目的观察高强度聚焦超声（HIFU）辐照靶区的回声增强与（生物学焦域中心）温度之间的关系。方法采用定点点打方式辐照牛肝组织，辐照声功率为65．44～196．32W，分为9级，每级相差16.36w，对应每级声功率辐照时间分别为1～20s；同一声功率和辐照时间下重复实验三次。辐照过程中，测温系统自动记录靶区中心温度；在辐照结束后采集靶区声像图，灰度定量软件自动读取感兴趣区灰度值。取靶区灰白色区域与正常组织交界处组织送病理检查（HE染色）。结果靶区温度低于65℃时，即使发生凝固性坏死，回声也不增强；而回声增强时对应焦域中心温度高于65℃。结论超声监控靶区回声增强与HIFU辐照靶区温度密切相关。

Objective To study the relationship between temperature and echo enhancement of target region radiated by HIFU. Methods Bovine hver was immersed into 0.9 % NS, degassed water in vitro for apphcation. Model JC focused ultrasound tumor therapeutic system and thermometry system were used in the experiment. HIFU parameters were： frequency： 1.6 MHz, depth： 20 mm, acoustic power from 16.44 W to 196.32 W. Under each power, radiation time was from 1 to 20 seconds. Pathologic examination was performed on all the samples. Results When the temperature of HIFU targeted region was lower than 65℃, though coagulative necrosis was observed, no echo enhancement was found. The obvious echo enhancement was observed when the temperature was higher than 65℃. Conclusion There is closely relationship between the temperature and the echo, ultrasound monitor is helpful to avoid tissue damage induced by large dose HIFU radiation.