A coupled subsample displacement estimation method for ultrasound-based strain elastography.
A coupled subsample displacement estimation method for ultrasound-based strain elastography.
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DOI：
10.1088/0031-9155/60/21/8347
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发表时间：
2015-11-07
影响因子：
3.5
通讯作者：
Hall TJ
中科院分区：
文献类型：
--
作者：
Jiang J;Hall TJ
获得沿轴向（平行于声束）和侧向（垂直于声束）方向的准确位移估计是许多临床应用的重要任务，例如剪切应变成像，模量重建和温度成像，其中需要二维或三维（2D/3D）变形场的完整描述。在这项研究中，我们提出了一种改进的散斑跟踪算法，其中轴向和横向运动估计同时进行，以提高运动跟踪精度。更具体地说，该算法首先利用常规超声回波数据，在变形前后两段超声射频回波数据的峰值相关附近找到一个等等值线。然后，该算法试图在这两段回波数据之间找到对应于未知（子样本）运动向量的相关函数的等等值线的中心。该算法已通过计算机模拟数据、组织模拟幻影研究和体内乳腺病变数据进行了测试。计算机仿真结果表明，该方法提高了横向和轴向跟踪的精度。当变形较小或沿侧向变形时，这种改善更为显著。组织模拟幻影研究的结果与计算机模拟中观察到的结果一致。使用体内乳腺病变数据，我们发现，与二维二次子样本位移估计方法相比，在多重压缩技术中，对于大变形（高达5%帧对帧和15%局部应变），可以获得更高质量的轴向应变和剪切应变图像（例如，剪切应变图像的噪比提高18.6%）。我们的初步结果表明，这种概念上和计算上简单的方法可以提高超声应变弹性成像（SE）的图像质量。
Obtaining accurate displacement estimates along both axial (parallel to the acoustic beam) and lateral (perpendicular to the beam) directions is an important task for several clinical applications such as shear strain imaging, modulus reconstruction and temperature imaging, where a full description of the two or three dimensional (2D/3D) deformation field is required. In this study we propose an improved speckle tracking algorithm where axial and lateral motion estimations are simultaneously performed to enhance motion tracking accuracy. More specifically, using conventional ultrasound echo data, this algorithm first finds an iso-contour in the vicinity of the peak correlation between two segments of the pre- and post-deformation ultrasound radiofrequency echo data. The algorithm then attempts to find the center of the iso-contour of the correlation function that corresponds to the unknown (sub-sample) motion vector between these two segments of echo data. This algorithm has been tested using computer-simulated data, studies with a tissue-mimicking phantom, and in vivo breast lesion data. Computer simulation results show that the method improves the accuracy of both lateral and axial tracking. Such improvements are more significant when the deformation is small or along the lateral direction. Results from the tissue-mimicking phantom study are consistent with findings observed in computer simulations. Using in vivo breast lesion data we found that, compared to the 2D quadratic subsample displacement estimation methods, higher quality axial strain and shear strain images (e.g. 18.6% improvement in contrast-to-noise ratio for shear strain images) can be obtained for large deformations (up to 5% frame-to-frame and 15% local strains) in a multi-compression technique. Our initial results demonstrated that this conceptually and computationally simple method could improve the image quality of ultrasound-based strain elastography (SE) with current clinical equipment.