University of Bern, Institute of Complementary Medicine, Bern, Switzerland.
University Hospital Zurich, University of Zurich, Department of Neonatology, Biomedical Optics Research Laboratory, Zurich, Switzerland.
Adv Exp Med Biol. 2018;1072:325-330. doi: 10.1007/978-3-319-91287-5_52.
Absolute optical properties (i.e., the absorption coefficient, μ, and the reduced scattering coefficient, [Formula: see text]) of head tissue can be measured with frequency-domain near-infrared spectroscopy (FD-NIRS).
We investigated how the absolute optical properties depend on the individual subject and the head region.
The data set used for the analysis comprised 31 single FD-NIRS measurements of 14 healthy subjects (9 men, 5 women, aged 33.4 ± 10.5 years). From an 8-min measurement (resting-state; FD-NIRS device: Imagent, ISS Inc.; bilateral over the prefrontal cortex, PFC, and visual cortex, VC) median values were calculated for μ and [Formula: see text] as well as the effective attenuation coefficient (μ) and the differential pathlength factor (DPF). The measurement was done for each subject one to three times with at least 24 h between the measurements.
(i) A Bayesian ANOVA analysis revealed that head region and subject were the most significant main effects on μ, [Formula: see text] and μ, as well as DPF, respectively. (ii) At the VC, μ, [Formula: see text] and μ had higher values compared to the PFC. (iii) The differences in the optical properties between PFC and VC were age-dependent. (iv) All optical properties also were age-dependent. This was strongest for the properties of the PFC compared to the VC.
Our analysis demonstrates that all optical head tissue properties (μ, [Formula: see text], μ and DPF) were dependent on the head region, individual subject and age. The optical properties of the head are like a 'fingerprint' for the individual subject. Assuming constant optical properties for the whole head should be carefully reconsidered.
频域近红外光谱（FD-NIRS）可测量头部组织的绝对光学特性（即吸收系数μ和散射系数[Formula: see text]）。
我们研究了绝对光学特性如何取决于个体和头部区域。
用于分析的数据组包括 14 名健康受试者（9 名男性，5 名女性，年龄 33.4±10.5 岁）的 31 次 FD-NIRS 单次测量。在 8 分钟的测量（静息状态；FD-NIRS 设备：Imagent，ISS Inc.；双侧前额叶皮层和视觉皮层，PFC 和 VC）中，计算了μ和[Formula: see text]以及有效衰减系数（μ）和差分路径长度因子（DPF）的中位数。每位受试者进行一次到三次测量，两次测量之间至少间隔 24 小时。
（i）贝叶斯方差分析显示，头部区域和个体是μ、[Formula: see text]和μ以及 DPF 的最显著主效应。（ii）在 VC 中，与 PFC 相比，μ、[Formula: see text]和μ的值更高。（iii）光学特性在 PFC 和 VC 之间的差异与年龄有关。（iv）所有光学特性也与年龄有关。与 VC 相比，PFC 的光学特性的年龄依赖性更强。
我们的分析表明，所有头部组织的光学特性（μ、[Formula: see text]、μ和 DPF）都取决于头部区域、个体和年龄。头部的光学特性就像个体的“指纹”。假设整个头部的光学特性是恒定的，应该仔细重新考虑。
