基于超声粒子成像技术的大鼠动脉模型血流剪切力测量方法

Measurement Method of Arterial Shear Stress of Rats Model Based on Ultrasonic Particle Imaging Velocimetry

动脉粥样硬化及血栓的形成与动脉管腔内的血流动力学参数变化密切相关。然而,目前普遍应用的超声多普勒成像技术不能精确测量复杂血流流场信息。本文提出了一种基于超声造影微泡的超声粒子成像测速技术,能够获得二维血管全流场的信息,且不依赖于声束与速度向量之间的夹角。本研究使用10只健康的大鼠,应用超声粒子成像测速法计算其左侧颈动脉的全场血流速度分布,结合多项式拟合的方法计算腔内速度梯度变化,可评估血管在不同血流速度下受到的剪切力。实验结果表明超声粒子成像技术测速结果与多普勒测速结果吻合。利用四次多项式拟合的正常血管流速模型效果最佳。统计血管壁周期的平均剪切力结果与该位置平均血流速度成正相关。超声粒子成像技术能够无创、实时地评估全流场血流动力学变化情况,为进一步探讨狭窄血管流场中复杂多变的剪切力分布异常奠定基础。

The development and progression of atherosclerosis and thrombosis are closely related to changes of hemo- dynamics parameters. Ultrasonic pulse wave Doppler technique is normally used for noninvasively blood flow ima- ging. However, this technique only provides one-dimensional velocity and depends on the angle between the ultra- sound beam and the local velocity vector. In this study, ultrasonic particle image veloeimetry method was used to as- sess whole field hemodynamic changes in normal blood vessels. By using the polynomial fitting method, we investi- gated the velocity gradient and assessed the shear in different blood flow velocity of 10 healthy rats. It was found that using four polynomial fitting could result in optimal measurement results. The results obtained by ultrasonic particle image velocimetry accorded with the results obtained using Doppler technique. The statistical average of cyclical ves- sel wall shear stress was positively related to the locational mean velocity. It is proven that ultrasonic particle image velocimetry method could be used to assess directly the real-time whole field hemodynamic changes in blood vessels and was non-invasively, and should be a good prosperous technique for monitoring complex blood flow in stenotic ar- teries.