血管腔内壁处轴向血流速度的径向变化率定义为血管壁面剪切率(Wall Shear Rate, WSR)。最新病理学研究结果表明，作为一种管壁内皮细胞基因表达调节机制，较低或震荡变化的WSR是动脉粥样硬化病变的重要诱因。应用超声技术获取WSR预测动脉粥样硬化病变是目前国内外的研究热点。然而使用超声直接检测WSR存在以下两个难点：1）有效抑制脉动血管壁及周围组织的低频高强度超声信号干扰；2）提高血管内壁周围轴向血流速度剖面的估计精度。项目拟基于非线性自适应信号处理理论，提出线阵超声扫描过程中可变或自适应调整脉冲发射间隔时间的思想，研究高性能搏动管壁与血流超声反射混合信号的分离方法，准确提取靠近管腔内壁周围的缓慢血流信号；研究自适应自相关血流速度剖面估计方法，准确检测管腔内壁周围慢速血流速度剖面；研究结果将有助于实现WSR的临床超声直接检测，对预测脑血管疾病的发生具有重要意义。

Wall shear rate (WSR) is defined as the radial velocity gradient in the radial direction for the axial blood blow close to the arterial walls. The latest pathological studies expose that as the gene expression and regulation mechanism of endothelial cells, lower and oscillatory WSR are essential to the foundation and development of atherosclerosis. It is a hotpot to acquire the WSR for prediction and quantification of atherosclerosis disease by using ultrasound technique. However, there are two difficulties for directly detection of the WSR: 1) effectively reject the disturbance from the pulsatile moving vessel wall; 2) improve the detection precision of the velocity profile of the blood flow close to the vessel wall. In present project, based on the nonlinear adaptive signal processing theory, we propose an ideal of variable or adaptive regulation for time intervals of pulse wave shooting during the ultrasonic scanning, and then will study the high performance separation approaches for the signals echoed from pulsatile blood and moving vessel walls to accurately extract the slow blood flow close to the vessel wall. We will study the approaches for autocorrelation estimation of blood flow velocity profile to accurately detection the velocity profile of the blood flow close to the vessel wall. The results could be helpful to realize the direct WSR detection in clinic, and be significant for providing evidences and methods for accurate prediction of atherosclerosis diseases.