Ultrasound based multiphysics imaging modalities: modelling, analysis and biomedical applications

本提案是关于利用基于多物理场的成像模式的图像建模和分析来研究生物组织和流体的新方法的发展。基于多物理场的成像是指利用两种物理效应共存或相互作用的事实，从而为观察生物组织或流体提供新的窗口的成像方式。给出了我们拟研究的三个实例。第一个例子是观察组织在磁场中产生的电场，而组织同时被失谐。在这里，超声波会使离子运动，而在磁场中运动的离子产生观察到的电势分布；因此，这种分布是一个时空信号，由发射的声信号、介质的声学特性、组织的电学特性和产生的磁场本身决定。第二个例子使用声光相互作用。超声信号被用来调制在组织中传播的光信号。通过适当的时间门控，将调制光信号识别为从特定组织区域发出。第三个例子涉及使用声辐射力使组织变形并使用散斑运动估计确定其刚度。在这里，连续介质力学的物理学与声学相结合。这项研究的最终目的是评估生物材料的某些基本物理性质。为了实现这一方法，研究项目分为三个部分：图像形成建模、信号分析和幻影实验。该方法有望在医学超声成像方面取得重大进展，并可能在涉及相干成像方式（如雷达和激光成像）的其他工程领域具有潜在的应用。

This proposal is about the development of new methods to study biological tissues and fluids using image modeling and analysis for multiphysics-based imaging modalities. By multiphysics-based imaging it is meant imaging modalities exploiting the fact that two physical effects either co-exist or interact with each other so that together they provide a new window to observe the biological tissue or fluid. Three examples we propose to study are given. A first example would be the observation of the electric field generated by a tissue in a magnetic field while the tissue is being simultaneously insonified.  Here the ultrasound would set ions in motion, and ions in motion in a magnetic field produce the observed electric potential distribution; this distribution is therefore a spatio-temporal signal determined by the emitted acoustic signal, the acoustic properties of the medium, the electrical properties of the tissue and the generated magnetic field itself. A second example uses acousto-optic interactions. Here an ultrasound signal is used to modulate an optical signal that propagates in the tissue. With appropriated time-gating the modulated optical signal is identified as being issued from a specific tissue region. The third example concerns the use of acoustic radiation force to deform a tissue and determine its stiffness using speckle motion estimation. Here the physics of continuum mechanics coupled to acoustics.   The purpose of this research is ultimately to assess certain fundamental physical properties of biological materials. To develop this approach, the research project is divided in three parts: image formation modeling, signal analysis and phantom experiments. The method is anticipated to provide a significant advance in medical ultrasonic imaging and may have potential applications in other engineering areas that involve a coherent imaging modality such as radar and laser imaging.