用于组织血流和光学参数同时测量的扩散散斑衬比分析方法研究

The blood flow and optical parameters (the absorption coefficient and the reduced scattering coefficient) of the tissue are important parameters for human body. Although the information of the change in a certain parameter can be provided by the existing imaging methods, it is difficult to simultaneously measure multiple parameters including blood flow, the absorption coefficient and the reduced scattering coefficient. Diffuse speckle contrast analysis (DSCA), i.e., the combination of the advantages of laser speckle contrast imaging (LSCI) and diffuse correlation spectroscopy (DCS), can measure deep tissue blood flow. Our previous study showed that the dependence of diffuse speckle contrast on the source-detector distance and exposure time could remove the strong coupling between the parameters and further confine the solution to a smaller area. Based on our previous study, the new DSCA model is built by the use of diffusion approximation theory and the information for the intensity of diffuse speckle in this project. The DSCA system for measuring multiple parameters is built by the combination of the hardware, the data acquisition software and the solution algorithm for the cost function in DSCA model. The accurate and stable measurements of multiple parameters for human forearm can be obtained by DSCA system. The measurements of the absorption coefficient at different wavelengths can be further used to obtain blood oxygen parameter. The research of this project will contribute to simultaneously measure the blood flow and optical parameters of the tissue and provide a new technical approach for comprehensively describing the tissue hemodynamics and metabolic characteristics.

组织的血流和光学参数（吸收系数和约化散射系数）是人体重要参数，现有的成像方法虽然能提供某一参数的变化信息，但难以实现血流、吸收系数和约化散射系数等多个参数的同时测量。扩散散斑衬比分析（DSCA）结合激光散斑衬比成像（LSCI）和扩散相关谱（DCS）两者的优势能够实现深层组织的血流测量，我们前期研究发现：利用扩散散斑衬比度与光源-探测器距离、曝光时间的函数关系，可以去除参数间强烈的耦合关系，减小参数解存在的空间。在前期研究基础上，本项目拟采用扩散近似理论，结合扩散散斑光强信息，建立新的DSCA多参数测量模型；结合硬件、数据采集软件和模型中代价函数求解算法，获得DSCA多参数测量系统，在人体前臂实现准确和稳定的多参数测量；进而利用不同波长的吸收系数测量结果，获得组织血氧参数。本项目的研究成果有助于实现组织血流和光学参数同时测量，为全面描述组织的血流动力学和新陈代谢特征提供新的技术途径。

扩散散斑衬比分析（DSCA）结合激光散斑衬比成像技术和扩散相关谱技术两者的优势能够实现深层组织的全场成像，DSCA因具有简单、全场、高时空分辨率等优势在生物组织血流监测中具有重大发展前景。目前，DSCA虽然能够提供组织血流的变化信息，但难以实现血流、吸收系数和约化散射系数等多个参数的同时测量。本项目针对半无限大组织介质，基于辐射传输方程和扩散近似理论，结合多距离多曝光扩散散斑衬比度信息（MDME-DSCA）和组织有效衰减系数，建立DSCA多参数测量目标函数；分析目标函数中组织吸收系数、约化散射系数、血流信息等参数灵敏度。研究结果表明：MDME-DSCA可以去除多个参数之间强烈的串扰关系，减小参数解存在的空间，在数值计算和实验实现了多参数重建；约化散射系数对散斑衬比度的影响最为显著，吸收系数的灵敏度要小于约化散射系数和血流信息；校正了相机噪声、统计噪声等对散斑衬比度的影响，提高多参数测量结果的准确性和稳定性。本文的研究结果为监测各种病理状态下组织体内部的血流状态和光学参数提供了一种理论根据。