一种测量液体声衰减的新方法:双界面回波法

血液超声衰减系数(ultrasoundary attenuation coefficient,USAC)与其生物物理特性有关,其在体测量具有重要的临床意义。作为USAC经典测量方法的插入替代法不适合在体测量,而由于血液自身散射较小,基于散射回波的在体测量方法也不适用于血液。为此本文提出一种新的测量液体衰减系数的方法——双界面回波法(dual-boundary echo comparison,DBEC)。该方法通过比较超声在液体和容器壁构成的界面上产生的前后两个回波的幅度比来估计液体的USAC。血管是血液的天然容器,血管壁回波比血液散射回波大,故DBEC方法有望克服现有方法的局限性。在通过体模实验验证DBEC方法的过程中,样品盒用有机玻璃制成,样品分别为蓖麻油和鸡血。实验所得到的蓖麻油USAC和参考资料的数值相差9.2%,而且观察到鸡血USAC随温度的变化情况。体模实验说明了DBEC方法的准确性和应用于血液的灵敏度,为DBEC的进一步在体实验打下了基础。

Dual-Boundary Echo Comparison: A Novel Method for Measurement of Ultrasound Attenuation in Fluid

Ultrasound attenuation coefficient （USAC） of blood characterizes its biophysical properties, whose in vivo measurement is important in clinical application. However the classical substitution method of USAC is not suitable for in vivo measurement, while the methods based on scattering echo do not apply to blood due to its weak scattering. In this paper, a novel method for measurement of ultrasound attenuation in fluid- dual-boundary echo comparison （DBEC） is presented. The method compared the amplitudes of anterior and posterior ultrasound echoes on the boundary between fluid and container wall to and estimate USAC of the fluid. Vessel is a natural container of blood, and echoes from vessel wall is far larger than blood scattering echoes, so it is possible to estimate the USAC by using DBEC method. We also implemented phantom experiment to test DBEC method with plexiglass as container and castor oil and chicken blood as sample. The relevant error of castor oil USAC between experiment measured and reference was 9.2%. Moreover, changes of chicken blood USAC with temperature were also detected. Phantom experiments presented accuracy of DBEC and the sensitivity to the blood application, which is the foundation for future in vivo experiments.