The SVD Beamformer: Physical Principles and Application to Ultrafast Adaptive Ultrasound
The SVD Beamformer: Physical Principles and Application to Ultrafast Adaptive Ultrasound
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DOI：
10.1109/tmi.2020.2986830
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发表时间：
2020-10-01
影响因子：
10.6
通讯作者：
Tanter, Mickael
中科院分区：
文献类型：
--
作者：
Bendjador, Hanna;Deffieux, Thomas;Tanter, Mickael
由于平面波或发散波相干复合技术的出现，生物医学超声技术正在发生范式的转变，从而加快了成像速度。剩下的一个挑战是处理超声在复杂层中传播时引起的相位和振幅畸变。与传统的逐线成像不同，超快超声每次传输都能提供整个成像区域的后向散射信息。本文利用这一特点，提出了一种快速像差校正的有效方法。我们的方法是基于一个包含多次平面波传输的背散射数据的超快复合矩阵的奇异值分解（SVD）。首先，我们解释了SVD和相关奇异向量在超快矩阵形式中的物理意义。我们从理论上证明了空间和角度变量的分离，通过SVD在超快数据上呈现，提供了一种优雅而直接的方法来优化后向散射数据的角相干性。在非均匀介质中，我们证明了第一空间和角度奇异向量分别检索感兴趣区域的无像差图像，以及其像差规律的相位和幅度。数值、体外和体内实验结果证明了图像校正的有效性，也证明了像差测定的准确性。基于空间和角相干性，我们介绍了一种完整的超快数据自适应波束形成方法，该方法在经过SVD波束形成的连续等平补丁上进行。该方法的简单性为实时自适应超快超声成像铺平了道路，并为未来超声定量应用提供了理论框架。
A shift of paradigm is currently underway in biomedical ultrasound thanks to plane or diverging waves coherent compounding for faster imaging. One remaining challenge consists in handling phase and amplitude aberrations induced during the ultrasonic propagation through complex layers. Unlike conventional line-per-line imaging, ultrafast ultrasound provides backscattering information from the whole imaged area for each transmission. Here, we take benefit from this feature and propose an efficient approach to perform fast aberration correction. Our method is based on the Singular Value Decomposition (SVD) of an ultrafast compound matrix containing backscattered data for several plane wave transmissions. First, we explain the physical signification of SVD and associated singular vectors within the ultrafast matrix formalism. We theoretically demonstrate that the separation of spatial and angular variables, rendered by SVD on ultrafast data, provides an elegant and straightforward way to optimize the angular coherence of backscattered data. In heterogeneous media, we demonstrate that the first spatial and angular singular vectors retrieve respectively the non-aberrated image of a region of interest, and the phase and amplitude of its aberration law. Numerical, in vitro and in vivo results prove the efficiency of the image correction, but also the accuracy of the aberrator determination. Based on spatial and angular coherence, we introduce a complete methodology for adaptive beamforming of ultrafast data, performed on successive isoplanatism patches undergoing SVD beamforming. The simplicity of this method paves the way to real-time adaptive ultrafast ultrasound imaging and provides a theoretical framework for future quantitative ultrasound applications.