Zhang Hongyan, Li Pengcheng, Feng Nengyun, Qiu Jianjun, Li Bing, Luo Weihua, Luo Qingming
Britton Chance Center for Biomedical Photonics, Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
Opt Express. 2012 Jan 2;20(1):508-17. doi: 10.1364/OE.20.000508.
Laser speckle spatial contrast analysis (LSSCA) is superior to laser speckle temporal contrast analysis (LSTCA) in monitoring the fast change in blood flow due to its advantage of high temporal resolution. However, the application of LSSCA which is based on spatial statistics may be limited when there is nonuniform intensity distribution such as fiber-transmitting laser speckle imaging. In this study, we present a normalized laser speckle spatial contrast analysis (nLSSCA) to correct the detrimental effects of nonuniform intensity distribution on the spatial statistics. Through numerical simulation and phantom experiments, it is found that just ten frames of dynamic laser speckle images are sufficient for nLSSCA to achieve effective correction. Furthermore, nLSSCA has higher temporal resolution than LSTCA to respond the change in velocity. LSSCA, LSTCA and nLSSCA are all applied in the fiber-transmitting laser speckle imaging system to analyze the change of cortical blood flow (CBF) during cortical spreading depression (CSD) in rat cortex respectively, and the results suggest that nLSSCA can examine the change of CBF more accurately. For these advantages, nLSSCA could be a potential tool for fiber-transmitting/endoscopic laser speckle imaging.
激光散斑空间对比度分析（LSSCA）在监测血流快速变化方面优于激光散斑时间对比度分析（LSTCA），因为它具有高时间分辨率的优势。然而，基于空间统计的LSSCA在存在强度分布不均匀的情况下（如光纤传输激光散斑成像）应用可能会受到限制。在本研究中，我们提出了一种归一化激光散斑空间对比度分析（nLSSCA），以纠正强度分布不均匀对空间统计的不利影响。通过数值模拟和体模实验发现，仅十帧动态激光散斑图像就足以使nLSSCA实现有效校正。此外，nLSSCA比LSTCA具有更高的时间分辨率来响应速度变化。LSSCA、LSTCA和nLSSCA均应用于光纤传输激光散斑成像系统，分别分析大鼠皮层皮层扩散性抑制（CSD）期间皮层血流（CBF）的变化，结果表明nLSSCA能够更准确地检测CBF的变化。基于这些优势，nLSSCA可能成为光纤传输/内窥镜激光散斑成像的潜在工具。
