Ultrasound elastography (USE) is an emerging noninvasive imaging technique in which pathological alterations can be visualized by revealing the mechanical properties of the tissue. Estimating tissue displacement in all directions is required to accurately estimate the mechanical properties. Despite capabilities of elastography techniques in estimating displacement in both axial and lateral directions, estimation of axial displacement is more accurate than lateral direction due to higher sampling frequency, higher resolution, and having a carrier signal propagating in the axial direction. Among different ultrasound imaging techniques, synthetic aperture (SA) has better lateral resolution than others, but it is not commonly used for USE due to its limitation in imaging depth of field. Virtual source synthetic aperture (VSSA) imaging is a technique to implement SA beamforming on the focused transmitted data to overcome the limitation of SA in depth of field while maintaining the same lateral resolution as SA. Besides lateral resolution, VSSA has the capability of increasing sampling frequency in the lateral direction without interpolation. In this article, we utilize VSSA to perform beamforming to enable higher resolution and sampling frequency in the lateral direction. The beamformed data are then processed using our recently published elastography technique, OVERWIND. Simulation and experimental results show substantial improvement in the estimation of lateral displacements.

中文翻译：

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用于超声弹性成像中精确横向位移估计的虚拟源合成孔径

超声弹性成像（USE）是一种新兴的非侵入性成像技术，其中可以通过揭示组织的机械特性来可视化病理改变。需要估算所有方向的组织位移才能准确估算机械性能。尽管弹性成像技术能够估计轴向和横向两个方向的位移，但是由于更高的采样频率，更高的分辨率以及在轴向上传播的载波信号，所以轴向位移的估计比横向方向更准确。在不同的超声成像技术中，合成孔径（SA）具有比其他更好的横向分辨率，但由于其对成像景深的限制，因此不常用于USE。虚拟源合成孔径（VSSA）成像是一种在聚焦的传输数据上实施SA波束成形以克服SA在景深方面的局限性，同时保持与SA相同的横向分辨率的技术。除了横向分辨率外，VSSA还具有在不进行插值的情况下提高横向采样频率的能力。在本文中，我们利用VSSA进行波束成形，以在横向方向上实现更高的分辨率和采样频率。然后使用我们最近发布的弹性成像技术OVERWIND处理波束形成的数据。仿真和实验结果表明，在估计横向位移方面有了实质性的改进。