Next generation of ultrasound strain imaging and elastography based on the coherent use of multiple transducers

超声弹性成像是一种测量组织力学性能的非侵入性成像技术。位移和应变测量依赖于超声数据的质量，如分辨率和对比度，而目前的弹性成像方法只能测量一个方向的位移。然而，软组织的力学性能不是各向同性的，而是在不同的方向上发生变化。因此，弹性成像测量将受益于多视角成像方法和成像灵敏度的提高。相干多换能器超声（CoMTUS）扩展了超声图像的有效孔径，直接提高了分辨率、对比度和视场（FOV）。这种多视角方法可用于改进二维/三维位移跟踪估计，并生成完整的应变场。本项目旨在将CoMTUS成像与弹性成像技术相结合，以提高位移测量的精度，并计算全应变张量。该方法包括三个主要步骤。首先，2D和3D跟踪方法将使用最先进的跟踪算法来实现射频数据或散斑跟踪。这将涉及根据跟踪算法的特点优化换能器和波束形成参数的分辨率、信噪比和视场。此外，应变和横波变形方法也将被研究和应用于多视图数据的开发。其次，基于所开发的二维/三维跟踪方法计算全应变场。将开发使用有限元建模、超声模拟和实验的验证框架，以测量各个方向的位移，并计算应变张量。最后，弹性成像的改进将使用校准幻影进行量化，并探讨未来可能的临床应用。

Ultrasound elastography is a non-invasive imaging technique for measuring the mechanical properties of tissue. Displacement and strain measurements are dependent on the quality of ultrasound data, such as resolution and contrast, and current elastography methods can only measure displacements in one direction. The mechanical properties of soft tissues however are not isotropic and change in different directions. Therefore, elastography measurements would benefit from multi-perspective imaging methods and improvements in imaging sensitivity.Coherent multi-transducer ultrasound (CoMTUS) extends the effective aperture of ultrasound images, directly improving the resolution, contrast, and field of view (FOV). This multi-perspective approach may be used to improve displacement tracking estimates in 2D/3D and generate a full strain field.This project aims to combine CoMTUS imaging with elastography techniques to improve the accuracy of displacement measurements and calculate the full strain tensor. The methodology contains three main steps. First, 2D and 3D tracking methods will be implemented using state-of-the-art tracking algorithms for either radiofrequency data or speckle tracking. This will involve optimizing the transducer and beamforming parameters for resolution, signal-to-noise ratio and FOV according to the features of the tracking algorithm. Also, strain and shear wave deformation methods will be investigated and adapted to exploit the multi-view data. Second, the full strain field will be calculated based on the 2D/3D tracking methods developed. Validation frameworks using finite element modelling, ultrasound simulations and experiments will be developed to measure the displacements in all directions and the strain tensor will be calculated.Finally, the improvements in elastography imaging will be quantified using calibration phantoms and possible future clinical applications will be explored.