动脉内中膜轴向脉动传播的局域脉搏波速超声检测研究

Pulse wave velocities (PWV) are optimized indices for quantitatively describing arterial stiffness. Owing to non-invasion, real time, and without blood pressure measurement, the method of the time transit (TT) based on an ultrasound is a hot area of research for detecting an local PWV. However, existing methods focus on measuring the time delay of the wall distension in a radial direction propagating along a segment of the artery to estimate PWVs. The location between a transducer and a vessel, and the acting force of a transducer on a vessel wall could be uneven. This can result in significant errors in the measurements of the time delays and PWVs. Recently, it has been found that the intima-media complex (IMC) of an artery pulsates in a axial (longitudinal) direction during a cardiac cycle under the influences of the stress of blood flow and tethering from adventitia and surrounding tissue. Because the IMC is located at the inner side of vessel lumen, the radial acting force effects little on the axial stress produced by the blood flow. Therefore, the IMC pulsation in an axial direction has a strong anti-interference capability. In the present project, by using ultrafast plane wave ultrasound, a novel idea is proposed to detect time delays based on the IMC axial distension transmitting along a segment of an artery for measuring local PWVs. First, a segment of a common carotid artery is scanned in the direction of pulse wave propagation by using coherent plane-wave compounding ultrasonography. The IMC axial distension waveforms at different beam positions are extracted from the B mode images by using a dynamically corrected 2D speckle tracking algorithm. The time delays and PWVs between any two adjacent beams and estimated. Finally, the mean PWV for the segment of the artery is calculated by a linear regression. The results could be helpful to improve accuracy and stability of PWV detection in clinic, and be significant for providing evidences and methods for the accurate prediction of atherosclerosis diseases

脉搏波传播速度(PWV)是动脉硬化定量描述的优选指标。超声时间传输法因无创、实时及无需血压测量等优点，是局域PWV检测的研究热点。然而现行方法中探头与血管段间的位置及作用力分布不均都会引起径向脉动检测波形的随机变化，造成延迟时间及PWV估计的显著误差。最新研究发现，受血流应力和组织牵引作用，血管壁内中膜复合体(IMC)也会发生轴向脉动。由于IMC位于管腔内侧，探头垂直作用力对轴向血流应力影响有限,其轴向脉动具有较强的抗扰性。项目拟应用平面波超快超声技术，提出检测IMC轴向脉动传播延迟的思想估计颈动脉局域PWV。首先应用平面波相干合成技术沿脉搏波传播方向对一段颈总动脉进行高帧频扫描，研究动态校正的2D斑点追踪提取声束位置处IMC的轴向脉动曲线，估计声束间脉搏波的延迟时间及PWV，并对整段血管的结果线性拟合获得PWV的均值。研究结果有望提高局域PWV检测精度及可靠性，为临床应用提供依据和手段。

按照计划任务书规定的内容，项目拟应用平面波超快超声技术，提出检测血管壁内中膜（Intima-Media complex, IMC）轴向脉动传播延迟的思想估计颈动脉局域PWV。首先应用平面波相干合成技术沿脉搏波传播方向对一段颈总动脉进行高帧频扫描，提出动态校正的2D斑点追踪提取声束位置处IMC的轴向脉动曲线，估计声束间脉搏波的延迟时间及PWV，并对整段血管的结果线性拟合获得PWV的均值。研究结果有望提高局域PWV检测精度及可靠性，为临床应用提供依据和手段。预期在国内外核心刊物上发表高质量的10篇期刊论文和3-4篇会议论文；获2项发明专利，2项软件著作权；培养8-10名硕士研究生，2-3名博士研究生。.按照计划书的要求，课题组首先进行了资料收集、整理，消化有关的资料，写出了综述文章；开展了同时描述轴径向运动的颈动脉三层膜超声动态仿真研究，建立了颈动脉脉搏波传播超声计算机仿真模型，比较研究了超声时间传输法和脉动环颈动脉局域脉搏波速检测性能，基于时间基准点估计颈动脉PWV的估计性能。提出了一种基于以实际基准点为中心模板的局部上冲段追踪（regional upstroke tracking, RUT）改进超声局部颈总动脉PWV的估计性能。研究了多角度平面波（Muti-angle plane Wave, MPW）相干复合血流速度检测的性能，提出了MPW相干复合的最优ST血流测速法，兼顾提高快速与慢速血流流速的测量精度；提出了极性平面波序列（Alternate Plane Wave Sequence, APWS）复用相干复合，改进了颈动脉血流速度剖面的估计精度。研究结果有助于提高对心脑血管硬化发生的认识，开发对这类疾病高危人群的筛选方法及对病情早期诊断、发展及治疗效果监测的有效、客观手段；为相关疾病高危人群风险预测和防治提供理论依据及实用的检测方法。.项目发表期刊论文17篇（通讯作者），其中SCI检索8篇(中科院一区1篇，二区6篇，三区1篇)，EI检索4篇，会议论文13篇（EI/ISTP检索，通讯作者）；主要成果发表在 “IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control,”，“Computer Methods and Programs in Biomedicine”、“Ultrasoni