Bioscience Division, Los Alamos National Laboratory, Los Alamos, P.O. Box 1663, MS M888, New Mexico 87544.
Jack D. Weiler Hospital, 1825 Eastchester Road, Room 3-37, Bronx, New York 10461.
J Biomed Opt. 2014 Mar;19(3):37004. doi: 10.1117/1.JBO.19.3.037004.
Tissue vasculature is altered when cancer develops. Consequently, noninvasive methods of monitoring blood vessel size, density, and oxygenation would be valuable. Simple spectroscopy employing fiber optic probes to measure backscattering can potentially determine hemoglobin parameters. However, heterogeneity of blood distribution, the dependence of the tissue-volume-sampled on scattering and absorption, and the potential compression of tissue all hinder the accurate determination of hemoglobin parameters. We address each of these issues. A simple derivation of a correction factor for the absorption coefficient, μa, is presented. This correction factor depends not only on the vessel size, as others have shown, but also on the density of blood vessels. Monte Carlo simulations were used to determine the dependence of an effective pathlength of light through tissue which is parameterized as a ninth-order polynomial function of μa. The hemoglobin bands of backscattering spectra of cervical tissue are fit using these expressions to obtain effective blood vessel size and density, tissue hemoglobin concentration, and oxygenation. Hemoglobin concentration and vessel density were found to depend on the pressure applied during in vivo acquisition of the spectra. It is also shown that determined vessel size depends on the blood hemoglobin concentration used.
当癌症发展时，组织脉管会发生改变。因此，监测血管大小、密度和氧合的非侵入性方法将非常有价值。简单的光谱学使用光纤探头测量背散射可以潜在地确定血红蛋白参数。然而，血液分布的异质性、组织体积对散射和吸收的依赖性以及组织的潜在压缩都阻碍了血红蛋白参数的准确确定。我们解决了这些问题中的每一个。提出了一种简单的吸收系数μa的校正因子的推导方法。正如其他人所表明的那样，这个校正因子不仅取决于血管大小，还取决于血管密度。蒙特卡罗模拟用于确定光通过组织的有效路径长度的依赖性，该依赖性被参数化为μa 的九阶多项式函数。使用这些表达式拟合颈组织背散射光谱的血红蛋白带，以获得有效血管大小和密度、组织血红蛋白浓度和氧合。发现血红蛋白浓度和血管密度取决于在体内获取光谱时施加的压力。还表明，确定的血管大小取决于所用的血液血红蛋白浓度。
