The objectives were to develop a novel three-dimensional technology for imaging naturally occurring shear wave (SW) propagation, demonstrate feasibility on human volunteers and quantify SW velocity in different propagation directions. Imaging of natural SWs generated by valve closures has emerged to obtain a direct measurement of cardiac stiffness. Recently, natural SW velocity was assessed in two dimensions on parasternal long axis view under the assumption of a propagation direction along the septum. However, in this approach the source localization and the complex three-dimensional propagation wave path was neglected making the speed estimation unreliable. High volume rate transthoracic acquisitions of the human left ventricle (1100 volume/s) was performed with a 4D ultrafast echocardiographic scanner. Four-dimensional tissue velocity cineloops enabled visualization of aortic and mitral valve closure waves. Energy and time of flight mapping allowed propagation path visualization and source localization, respectively. Velocities were quantified along different directions. Aortic and mitral valve closure SW velocities were assessed for the three volunteers with low standard deviation. Anisotropic propagation was also found suggesting the necessity of using a three-dimensional imaging approach. Different velocities were estimated for the three directions for the aortic (3.4± 0.1 m/s, 3.5± 0.3 m/s, 5.4± 0.7 m/s) and the mitral (2.8± 0.5 m/s, 2.9± 0.3 m/s, 4.6± 0.7 m/s) valve SWs. 4D ultrafast ultrasound alleviates the limitations of 2D ultrafast ultrasound for cardiac SW imaging based on natural SW propagations and enables a comprehensive measurement of cardiac stiffness. This technique could provide stiffness mapping of the left ventricle.

中文翻译：

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人心脏中自然产生的剪切波的4D超快超声成像。

目的是开发一种新颖的三维技术，用于对自然发生的剪切波（SW）传播进行成像，证明对人类志愿者的可行性，并量化不同传播方向上的SW速度。出现了由瓣膜关闭产生的天然SW的成像，可直接测量心脏的僵硬度。最近，在沿胸骨旁长轴的假想中，在沿胸骨旁长轴视图的二维上评估了自然西南向速度。然而，在这种方法中，由于忽略了源定位和复杂的三维传播波路径，因此速度估算不可靠。使用4D超快速超声心动图扫描仪对人的左心室进行高体积率经胸腔采集（1100体积/秒）。二维组织速度电影环使主动脉和二尖瓣闭合波的可视化成为可能。能量和飞行时间映射分别允许传播路径可视化和源定位。沿不同方向量化速度。对三名标准偏差低的志愿者评估了主动脉和二尖瓣关闭的SW速度。还发现各向异性传播，表明使用三维成像方法的必要性。主动脉（3.4±0.1 m / s，3.5±0.3 m / s，5.4±0.7 m / s）和二尖瓣（2.8±0.5 m / s，2.9±0.3 m / s）的三个方向的估计速度不同，4.6±0.7 m / s）阀门SW。4D超快超声减轻了基于自然SW传播的2D超快超声在心脏SW成像中的局限性，并能够全面测量心脏硬度。该技术可以提供左心室的刚度图。