Rege Abhishek, Murari Kartikeya, Li Nan, Thakor Nitish V
Department of Biomedical Engineering at the Johns Hopkins University, Baltimore, MD 21205, USA.
Annu Int Conf IEEE Eng Med Biol Soc. 2010;2010:1978-81. doi: 10.1109/IEMBS.2010.5627543.
Laser speckle contrast imaging (LSCI) has classically been used to image regional blood flow changes in animal models. In this paper, we demonstrate the use of LSCI for elucidating blood flow characteristics in individual microvessels with diameters as small as 24µm. We extracted profiles of speckle contrast values within individual vessels, both along their diameters and along their lengths and inferred that they could be attributed to the flow within the vessel. Profiles along the diameter of vessels revealed maxima at the center of vessels, consistent with fluid dynamics. These observed profiles could be fitted with parabolic curves with a mean coefficient of determination of 0.92. Similarly, analysis of speckle contrast values in the axial direction revealed profiles that progressively decreased in discreet quanta at branch points indicating blood flow bifurcations. Flow estimates obtained from speckle contrast values within branches of vessels obeyed the law of mass conservation with a mean error of only 3.5%. This allowed us to elucidate the percentage distribution of blood flow into each of the downstream branches. This ability of LSCI to resolve blood flow distribution in branching microvessel trees in a minimally invasive and dye free environment over a wide field of view promises to find application in both the neuroscience laboratory as well as intraoperative neurosurgery.
激光散斑对比成像（LSCI）传统上用于对动物模型中的局部血流变化进行成像。在本文中，我们展示了使用LSCI来阐明直径小至24µm的单个微血管中的血流特征。我们提取了单个血管内沿其直径和长度的散斑对比值曲线，并推断它们可归因于血管内的血流。沿血管直径的曲线显示血管中心处有最大值，这与流体动力学一致。这些观察到的曲线可以用抛物线拟合，平均决定系数为0.92。同样，对轴向散斑对比值的分析显示，在分支点处曲线以离散量子逐渐下降，表明血流分支。从血管分支内的散斑对比值获得的血流估计值符合质量守恒定律，平均误差仅为3.5%。这使我们能够阐明流入每个下游分支的血流百分比分布。LSCI在微创且无染料的环境中，在宽视野范围内解析分支微血管树中血流分布的这种能力有望在神经科学实验室以及术中神经外科手术中得到应用。
