Department of Bioengineering, Imperial College London, Prince Consort Road, London, SW7 2AZ, UK.
Ann Biomed Eng. 2020 Jun;48(6):1728-1739. doi: 10.1007/s10439-020-02484-2. Epub 2020 Mar 4.
Abnormal blood flow and wall shear stress (WSS) can cause and be caused by cardiovascular disease. To date, however, no standard method has been established for mapping WSS in vivo. Here we demonstrate wide-field assessment of WSS in the rabbit abdominal aorta using contrast-enhanced ultrasound image velocimetry (UIV). Flow and WSS measurements were made independent of beam angle, curvature or branching. Measurements were validated in an in silico model of the rabbit thoracic aorta with moving walls and pulsatile flow. Mean errors over a cardiac cycle for velocity and WSS were 0.34 and 1.69%, respectively. In vivo time average WSS in a straight segment of the suprarenal aorta correlated highly with simulations (PC = 0.99) with a mean deviation of 0.29 Pa or 5.16%. To assess fundamental plausibility of the measurement, UIV WSS was compared to an analytic approximation derived from the Poiseuille equation; the discrepancy was 17%. Mapping of WSS was also demonstrated in regions of arterial branching. High time average WSS (TAWSS = 3.4 Pa) and oscillatory flow (OSI = 0.3) were observed near the origin of conduit arteries. In conclusion, we have demonstrated that contrast-enhanced UIV is capable of measuring spatiotemporal variation in flow velocity, arterial wall location and hence WSS in vivo with high accuracy over a large field of view.
异常的血流和壁切应力（WSS）可导致心血管疾病，并可由心血管疾病引起。然而，迄今为止，尚未建立用于体内映射 WSS 的标准方法。在这里，我们使用对比增强超声图像速度（UIV）演示了在兔腹主动脉中进行 WSS 的宽视场评估。流量和 WSS 的测量与波束角度、曲率或分支无关。在具有移动壁和脉动流的兔胸主动脉的计算机模拟中验证了测量值。心动周期内速度和 WSS 的平均误差分别为 0.34%和 1.69%。在肾上段主动脉的直段内进行的体内平均壁切应力与模拟高度相关（PC=0.99），平均偏差为 0.29 Pa 或 5.16%。为了评估测量的基本合理性，将 UIV WSS 与从泊肃叶方程得出的解析近似值进行了比较；差异为 17%。在动脉分支区域也进行了 WSS 映射。在导管动脉起源附近观察到高时间平均壁切应力（TAWSS=3.4 Pa）和振荡流（OSI=0.3）。总之，我们已经证明，对比增强 UIV 能够以高精度在大视场范围内测量体内血流速度、动脉壁位置以及因此的 WSS 的时空变化。
