Yoshida Keiichiro, Nishidate Izumi, Ishizuka Tomohiro, Kawauchi Satoko, Sato Shunichi, Sato Manabu
Tokyo University of Agriculture & Technology, Graduate School of Bio-Application & Systems Engineering, Koganei, Tokyo 184-8588, Japan.
National Defense Medical College Research Institute, Division of Biomedical Information Sciences, Tokorozawa, Saitama 359-8513, Japan.
J Biomed Opt. 2015 May;20(5):051026. doi: 10.1117/1.JBO.20.5.051026.
In order to estimate multispectral images of the absorption and scattering properties in the cerebral cortex of in vivo rat brain, we investigated spectral reflectance images estimated by the Wiener estimation method using a digital RGB camera. A Monte Carlo simulation-based multiple regression analysis for the corresponding spectral absorbance images at nine wavelengths (500, 520, 540, 560, 570, 580, 600, 730, and 760 nm) was then used to specify the absorption and scattering parameters of brain tissue. In this analysis, the concentrations of oxygenated hemoglobin and that of deoxygenated hemoglobin were estimated as the absorption parameters, whereas the coefficient a and the exponent b of the reduced scattering coefficient spectrum approximated by a power law function were estimated as the scattering parameters. The spectra of absorption and reduced scattering coefficients were reconstructed from the absorption and scattering parameters, and the spectral images of absorption and reduced scattering coefficients were then estimated. In order to confirm the feasibility of this method, we performed in vivo experiments on exposed rat brain. The estimated images of the absorption coefficients were dominated by the spectral characteristics of hemoglobin. The estimated spectral images of the reduced scattering coefficients had a broad scattering spectrum, exhibiting a larger magnitude at shorter wavelengths, corresponding to the typical spectrum of brain tissue published in the literature. The changes in the estimated absorption and scattering parameters during normoxia, hyperoxia, and anoxia indicate the potential applicability of the method by which to evaluate the pathophysiological conditions of in vivo brain due to the loss of tissue viability.
为了估计活体大鼠脑皮质中吸收和散射特性的多光谱图像，我们研究了使用数字RGB相机通过维纳估计方法估计的光谱反射率图像。然后，针对九个波长（500、520、540、560、570、580、600、730和760 nm）处的相应光谱吸光度图像，进行了基于蒙特卡罗模拟的多元回归分析，以确定脑组织的吸收和散射参数。在该分析中，将氧合血红蛋白浓度和脱氧血红蛋白浓度估计为吸收参数，而将通过幂律函数近似的约化散射系数谱的系数a和指数b估计为散射参数。从吸收和散射参数重建吸收系数谱和约化散射系数谱，然后估计吸收系数谱和约化散射系数谱的光谱图像。为了证实该方法的可行性，我们对暴露的大鼠脑进行了活体实验。吸收系数的估计图像主要由血红蛋白的光谱特征主导。约化散射系数的估计光谱图像具有较宽的散射光谱，在较短波长处呈现出较大的幅度，这与文献中发表的脑组织典型光谱相对应。常氧、高氧和缺氧期间估计的吸收和散射参数的变化表明，该方法具有评估因组织活力丧失导致的活体脑病理生理状况的潜在适用性。
