Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts.
School of Engineering, Institute for Brain Science, Brown University, Providence, Rhode Island.
J Biophotonics. 2018 Feb;11(2). doi: 10.1002/jbio.201700070. Epub 2017 Aug 9.
Quantitative measurements of intravascular microscopic dynamics, such as absolute blood flow velocity, shear stress and the diffusion coefficient of red blood cells (RBCs), are fundamental in understanding the blood flow behavior within the microcirculation, and for understanding why diffuse correlation spectroscopy (DCS) measurements of blood flow are dominantly sensitive to the diffusive motion of RBCs. Dynamic light scattering-optical coherence tomography (DLS-OCT) takes the advantages of using DLS to measure particle flow and diffusion within an OCT resolution-constrained three-dimensional volume, enabling the simultaneous measurements of absolute RBC velocity and diffusion coefficient with high spatial resolution. In this work, we applied DLS-OCT to measure both RBC velocity and the shear-induced diffusion coefficient within penetrating venules of the somatosensory cortex of anesthetized mice. Blood flow laminar profile measurements indicate a blunted laminar flow profile and the degree of blunting decreases with increasing vessel diameter. The measured shear-induced diffusion coefficient was proportional to the flow shear rate with a magnitude of ~0.1 to 0.5 × 10 mm . These results provide important experimental support for the recent theoretical explanation for why DCS is dominantly sensitive to RBC diffusive motion.
血管内微观动力学的定量测量，如血流速度、剪切应力和红细胞（RBC）的扩散系数，是理解微循环内血流行为的基础，也有助于理解为什么漫射相关光谱（DCS）测量血流主要对 RBC 的扩散运动敏感。动态光散射-光学相干断层扫描（DLS-OCT）利用 DLS 来测量 OCT 分辨率限制的三维体积内的粒子流动和扩散，从而实现了 RBC 速度和扩散系数的高空间分辨率的同步测量。在这项工作中，我们应用 DLS-OCT 来测量麻醉小鼠体感皮层穿透小静脉内的 RBC 速度和剪切诱导的扩散系数。血流层流轮廓测量表明层流轮廓变钝，且钝度随血管直径的增加而减小。测量得到的剪切诱导扩散系数与流动剪切率成正比，量级为~0.1 至 0.5×10^-6 mm^2/s。这些结果为 DCS 主要对 RBC 扩散运动敏感的最新理论解释提供了重要的实验支持。
