反蒙特卡罗在多层组织模型中的应用：漫反射光谱和激光多普勒流量测量的融合。

Inverse Monte Carlo in a multilayered tissue model: merging diffuse reflectance spectroscopy and laser Doppler flowmetry.

机构信息

Linköping University, Department of Biomedical Engineering, University Hospital, 581 85 Linköping, SwedenbPerimed AB, Datavägen 9A, 175 43 Järfälla, Sweden.

Linköping University, Department of Mathematics, Division of Optimization, 581 83 Linköping, Sweden.

出版信息

J Biomed Opt. 2013 Dec;18(12):127004. doi: 10.1117/1.JBO.18.12.127004.

DOI:10.1117/1.JBO.18.12.127004

PMID:24352692

Abstract

The tissue fraction of red blood cells (RBCs) and their oxygenation and speed-resolved perfusion are estimated in absolute units by combining diffuse reflectance spectroscopy (DRS) and laser Doppler flowmetry (LDF). The DRS spectra (450 to 850 nm) are assessed at two source-detector separations (0.4 and 1.2 mm), allowing for a relative calibration routine, whereas LDF spectra are assessed at 1.2 mm in the same fiber-optic probe. Data are analyzed using nonlinear optimization in an inverse Monte Carlo technique by applying an adaptive multilayered tissue model based on geometrical, scattering, and absorbing properties, as well as RBC flow-speed information. Simulations of 250 tissue-like models including up to 2000 individual blood vessels were used to evaluate the method. The absolute root mean square (RMS) deviation between estimated and true oxygenation was 4.1 percentage units, whereas the relative RMS deviations for the RBC tissue fraction and perfusion were 19% and 23%, respectively. Examples of in vivo measurements on forearm and foot during common provocations are presented. The method offers several advantages such as simultaneous quantification of RBC tissue fraction and oxygenation and perfusion from the same, predictable, sampling volume. The perfusion estimate is speed resolved, absolute (% RBC×mm/s), and more accurate due to the combination with DRS.

摘要

通过结合漫反射光谱（DRS）和激光多普勒流量测量（LDF），以绝对单位估计红细胞（RBC）的组织分数及其氧合和速度分辨灌注。DRS 光谱（450 至 850nm）在两个源探测器分离（0.4 和 1.2mm）处进行评估，允许进行相对校准程序，而 LDF 光谱在同一光纤探头的 1.2mm 处进行评估。使用基于几何形状、散射和吸收特性以及 RBC 流速信息的自适应分层组织模型，通过应用逆蒙特卡罗技术中的非线性优化对数据进行分析。使用包括多达 2000 个单独血管的 250 个组织样模型进行了模拟，以评估该方法。估计的和真实氧合之间的绝对均方根（RMS）偏差为 4.1%，而 RBC 组织分数和灌注的相对 RMS 偏差分别为 19%和 23%。还展示了在常见刺激期间前臂和脚部的体内测量示例。该方法具有几个优点，例如可以从相同的、可预测的采样体积同时定量 RBC 组织分数、氧合和灌注。由于与 DRS 相结合，灌注估计是速度分辨的、绝对的（% RBC×mm/s），并且更准确。