Opt Express. 2024 Feb 26;32(5):6887-6902. doi: 10.1364/OE.510874.
Laser speckle contrast imaging (LSCI) has gained significant attention in the biomedical field for its ability to map the spatio-temporal dynamics of blood perfusion in vivo. However, LSCI faces difficulties in accurately resolving blood perfusion in microvessels. Although the transmissive detecting geometry can improve the spatial resolution of tissue imaging, ballistic photons directly transmitting forward through tissue without scattering will cause misestimating in the flow speed by LSCI because of the lack of a quantitative theoretical model of transmissvie LSCI. Here, we develop a model of temporal LSCI which accounts for the effect of nonscattered light on estimating decorrelation time. Based on this model, we further propose a dual-exposure temporal laser speckle imaging method (dEtLSCI) to correct the overestimation of background speed when performing traditional transmissive LSCI, and reconstruct microvascular angiography using the scattered component extracted from total transmitted light. Experimental results demonstrated that our new method opens an opportunity for LSCI to simultaneously resolve the blood vessels morphology and blood flow speed at microvascular level in various contexts, ranging from the drug-induced vascular response to angiogenesis and the blood perfusion monitoring during tumor growth.
激光散斑对比成像（LSCI）在生物医学领域中受到了广泛关注，因为它能够对体内血液灌注的时空动力学进行成像。然而，LSCI 在准确解析微血管中的血液灌注方面存在困难。虽然透射检测几何结构可以提高组织成像的空间分辨率，但由于缺乏对透射 LSCI 的定量理论模型，直接通过组织向前传输的弹道光子没有散射，会导致 LSCI 对血流速度的估计出现偏差。在这里，我们开发了一种考虑非散射光对估计去相关时间影响的时间 LSCI 模型。基于这个模型，我们进一步提出了一种双曝光时间激光散斑成像方法（dEtLSCI），用于纠正传统透射 LSCI 中背景速度的高估，并利用从总透射光中提取的散射分量来重建微血管造影。实验结果表明，我们的新方法为 LSCI 提供了一个机会，可以在各种情况下同时解析微血管水平的血管形态和血流速度，从药物诱导的血管反应到血管生成以及肿瘤生长过程中的血液灌注监测。
