Traditional two-dimensional (2D) ultrasound speckle tracking echocardiography (STE) studies have shown a wide range of twist values, also for normal hearts, which is due to the limitations of short-axis 2D ultrasound. The same limitations do not apply to three-dimensional (3D) ultrasound, and several studies have shown 3D ultrasound to be superior to 2D ultrasound, which is unreliable for measuring twist. The aim of this study was to develop a left ventricular twisting phantom and to evaluate the accuracy of 3D STE twist measurements using different acquisition methods and volume rates (VR). This phantom was not intended to simulate a heart, but to function as a medium for ultrasound deformation measurement. The phantom was made of polyvinyl alcohol (PVA) and casted using 3D printed molds. Twist was obtained by making the phantom consist of two PVA layers with different elastic properties in a spiral pattern. This gave increased apical rotation with increased stroke volume in a mock circulation. To test the accuracy of 3D STE twist, both single-beat, as well as two, four and six multi-beat acquisitions, were recorded and compared against twist from implanted sonomicrometry crystals. A custom-made software was developed to calculate twist from sonomicrometry. The phantom gave sonomicrometer twist values from 2.0° to 13.8° depending on the stroke volume. STE software tracked the phantom wall well at several combinations of temporal and spatial resolution. Agreement between the two twist methods was best for multi-beat acquisitions in the range of 14.4–30.4 volumes per second (VPS), while poorer for single-beat and higher multi-beat VRs. Smallest offset was obtained at six-beat multi-beat at 17.1 VPS and 30.4 VPS. The phantom proved to be a useful tool for simulating cardiac twist and gave different twist at different stroke volumes. Best agreement with the sonomicrometer reference method was obtained at good spatial resolution (high beam density) and a relatively low VR. 3D STE twist values showed better agreement with sonomicrometry for most multi-beat recordings compared with single-beat recordings.

中文翻译：

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用于3D超声心动图扭曲测量的左心室幻影。

传统的二维（2D）超声斑点跟踪超声心动图（STE）研究显示，对于正常心脏，扭曲值也很宽，这是由于短轴2D超声的局限性所致。相同的限制不适用于三维（3D）超声，并且一些研究表明3D超声优于2D超声，这对于测量扭曲是不可靠的。这项研究的目的是开发一种左心室扭曲体模，并使用不同的采集方法和体积率（VR）评估3D STE扭曲测量的准确性。该体模并非旨在模拟心脏，而是用作超声变形测量的媒介。幻影由聚乙烯醇（PVA）制成，并使用3D打印模具铸造。通过使体模由具有不同弹性特性的两个PVA层组成螺旋形图案来获得扭曲。在模拟循环中，这增加了心尖旋转并增加了搏动量。为了测试3D STE扭曲的准确性，记录了单拍以及两个，四个和六个多拍的采集数据，并与植入的体测法晶体的扭曲进行了比较。开发了一种定制软件，用于根据体测法计算扭曲。幻象根据行程量给出的转速计扭曲值为2.0°至13.8°。STE软件以时间和空间分辨率的几种组合很好地跟踪了幻影墙。两种扭曲方法之间的协议最适合于每秒14.3–30.4音量（VPS）范围内的多拍采集，而对于单拍和更高的多拍VR则较差。在17.1 VPS和30.4 VPS的六拍多拍时获得了最小的偏移。幻象被证明是模拟心脏扭曲的有用工具，并且在不同的搏动量下具有不同的扭曲。在良好的空间分辨率（高光束密度）和相对较低的VR下，获得了与频率计参考方法的最佳一致性。与单拍记录相比，对于大多数多拍记录，3D STE扭曲值与体测法显示出更好的一致性。在良好的空间分辨率（高光束密度）和相对较低的VR下，获得了与频率计参考方法的最佳一致性。与单拍记录相比，对于大多数多拍记录，3D STE扭曲值与体测法显示出更好的一致性。在良好的空间分辨率（高光束密度）和相对较低的VR下，获得了与频率计参考方法的最佳一致性。与单拍记录相比，对于大多数多拍记录，3D STE扭曲值与体测法显示出更好的一致性。