Establishing the diffuse correlation spectroscopy signal relationship with blood flow
Establishing the diffuse correlation spectroscopy signal relationship with blood flow
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DOI：
10.1117/1.nph.3.3.031412
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发表时间：
2016-07-01
期刊：
影响因子：
5.3
通讯作者：
Carp, Stefan A.
中科院分区：
文献类型：
--
作者：
Boas, David A.;Sakadzic, Sava;Carp, Stefan A.
漫射相关光谱（DCS）测量血流依赖于漫射散射光的时间自相关函数对红细胞（RBC）均方位移（MSD）的敏感性。对于以对流速度v（RBC）流动的红细胞，预计自相关将随着(v(RBC)(tau))(2)呈指数衰减，其中tau是延迟时间。红细胞也经历剪切诱导扩散，其扩散系数为D-shear， MSD为6D（剪切）tau。令人惊讶的是，实验数据主要反映了扩散行为。为了提供对流和扩散运动相对贡献的定量估计，我们对不同血管密度的组织中的光散射进行了蒙特卡罗模拟。我们假设层流血管流动剖面，并考虑剪切引起的扩散效应。与实验数据一致，我们发现扩散运动主导了典型DCS测量参数的相关衰减。此外，我们的模型提供了红细胞扩散系数和绝对组织血流量之间的定量关系。因此，我们首次为经验上公认的DCS血流指数（BFi）量化组织灌注的能力提供了理论支持。我们发现BFi与血流量成线性比例，但比例由血红蛋白浓度和平均血管直径调节。(C)作者。
Diffuse correlation spectroscopy (DCS) measurements of blood flow rely on the sensitivity of the temporal autocorrelation function of diffusively scattered light to red blood cell (RBC) mean square displacement (MSD). For RBCs flowing with convective velocity v(RBC), the autocorrelation is expected to decay exponentially with (v(RBC)(tau))(2), where tau is the delay time. RBCs also experience shear-induced diffusion with a diffusion coefficient D-shear and an MSD of 6D(shear)tau. Surprisingly, experimental data primarily reflect diffusive behavior. To provide quantitative estimates of the relative contributions of convective and diffusive movements, we performed Monte Carlo simulations of light scattering through tissue of varying vessel densities. We assumed laminar vessel flow profiles and accounted for shear-induced diffusion effects. In agreement with experimental data, we found that diffusive motion dominates the correlation decay for typical DCS measurement parameters. Furthermore, our model offers a quantitative relationship between the RBC diffusion coefficient and absolute tissue blood flow. We thus offer, for the first time, theoretical support for the empirically accepted ability of the DCS blood flow index (BFi) to quantify tissue perfusion. We find BFi to be linearly proportional to blood flow, but with a proportionality modulated by the hemoglobin concentration and the average blood vessel diameter. (C) The Authors.