基于结构光照明的快速高分辨激光散斑血流成像技术研究

Blood flow is an important index of measuring tissue function state. Laser speckle blood flow imaging is a label-free, high spatiotemporal resolution technique, and has become an important tool for real-time in vivo monitoring tissue blood flow changes. However, conventional laser speckle blood flow imaging method is based on single scattering assumption, and cannot accurately obtain two-dimensional tissue blood flow in the condition of multiple scattering, which is the main bottleneck of restricting the development of this technique. In this project, we intend to adopt structured illumination to suppress the effect of the scattered light from deep-tissue. Furthermore, through combining this technique with the spatial cross correlation coefficient method, we aim to suppress the effect of static scattered light from tissue surface, and meanwhile maintain high imaging speed. We also intend to study the characteristics of fluid motion, and establish the field autocorrelation function for a non-monotonic motion model. Through investigating the spatiotemporal characterization of the Gamma distributed speckles, we aim to establish a speckle contrast calibration method at various imaging system parameters. In brief, this project aims to develop an optical imaging method which possesses the abilities of deeper imaging depth, higher measurement accuracy, and meanwhile has the ability of real-time imaging of multi-parameter information from blood flow images. This project is expected to provide an important tool for investigating neural-vascular coupling mechanism, disease pathogenesis and treatment methods.

血流是衡量组织机能状态的重要指标。激光散斑血流成像无需造影剂、时空分辨率高，已成为实时在体监测组织血流变化的重要手段。然而，传统激光散斑血流成像方法基于单次散射假设，无法准确获取多次散射条件下组织二维血流速度信息，是制约该技术发展的主要瓶颈。本项目拟采用基于高速数字微镜器件的结构光照明方法，实现深层散射光干扰的抑制；结合互相关系数求解方法，在保证高速成像的同时，实现表层静态散射光干扰的抑制；研究流体运动特性，建立非单一运动模型下的散射光电场自相关函数；对Gamma分布的散斑时空统计特性进行分析，建立不同成像系统参数下的散斑衬比校正方法，使成像结果具有一致性和可重复性。本项目旨在发展提高激光散斑血流成像的成像深度、血流检测准确性，同时具备血流图像多参数信息实时成像能力的光学成像方法，为研究神经-血管耦合机制、疾病发病机理和治疗方法提供重要研究手段。

激光散斑血流成像无需造影剂、时空分辨率高，已成为 实时在体监测组织血流变化的重要手段。本项目针对激光散斑血流成像中多次散射、成像系统噪声等因素影响对流速测量准确性的影响进行了定量研究，并提出相关校正方法，取得了系列研究成果。提出了基于结构光照明及波前编码照明光束相位调制的激光散斑成像技术，实现了对高散射背景下的运动介质的运动速度进行非接触式高分辨率测量。对成像系统光子噪声、暗噪声影响进行了定量分析并提出散斑流速测量校正公式，显著提升了激光散斑流速测量准确性和一致性。提出了单个曝光时间下的最优化激光散斑流速测量公式，实现了实时高分辨率流速准确测量。发展了基于激光散斑成像的生物组织粘弹性测量方法。本项目研究工作通过理论分析与实验研究相结合，解决了多次散射、成像系统噪声等多因素影响条件下的定量化激光散斑流速测量问题，相关研究成果将为研究神经-血管耦合机制、疾病发病机理和治疗方法提供重要研究手段。