Speckle tracking echocardiography (STE) is a clinical tool to noninvasively assess regional myocardial function through the quantification of regional motion and deformation. Even if the time resolution of STE can be improved by high-frame-rate (HFR) imaging, dedicated HFR STE algorithms have to be developed to detect very small interframe motions. Therefore, in this article, we propose a novel 2-D STE method, purposely developed for HFR echocardiography. The 2-D motion estimator consists of a two-step algorithm based on the 1-D cross correlations to separately estimate the axial and lateral displacements. The method was first optimized and validated on simulated data giving an accuracy of ~3.3% and ~10.5% for the axial and lateral estimates, respectively. Then, it was preliminarily tested in vivo on ten healthy volunteers showing its clinical applicability and feasibility. Moreover, the extracted clinical markers were in the same range as those reported in the literature. Also, the estimated peak global longitudinal strain was compared with that measured with a clinical scanner showing good correlation and negligible differences (−20.94% versus −20.31%, ${p}$ -value = 0.44). In conclusion, a novel algorithm for STE was developed: the radio frequency (RF) signals were preferred for the axial motion estimation, while envelope data were preferred for the lateral motion. Furthermore, using 2-D kernels, even for 1-D cross correlation, makes the method less sensitive to noise.

中文翻译：

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高帧速超声心动图的新型二维斑点跟踪方法。

斑点追踪超声心动图（STE）是一种通过量化区域运动和变形来无创评估区域心肌功能的临床工具。即使可以通过高帧率（HFR）成像提高STE的时间分辨率，也必须开发专用的HFR STE算法以检测非常小的帧间运动。因此，在本文中，我们提出了一种新颖的二维STE方法，专门用于HFR超声心动图。2-D运动估算器由基于1-D互相关的两步算法组成，分别估算轴向和横向位移。该方法首先在模拟数据上进行了优化和验证，轴向和横向估计的准确度分别为〜3.3％和〜10.5％。然后，经过初步测试体内在十名健康志愿者身上展示了其临床适用性和可行性。此外，提取的临床标志物与文献报道的范围相同。此外，将估计的峰值总纵向应变与使用临床扫描仪测得的峰值进行了比较，显示出良好的相关性和可忽略的差异（−20.94％对−20.31％， $ {p} $ -值= 0.44）。总之，开发了一种新颖的STE算法：轴向运动估计首选射频（RF）信号，而横向运动首选包络数据。此外，即使对于一维互相关，使用2-D内核也会使该方法对噪声的敏感性降低。