Alternative Title頭部構造と各層内血流変化が光マッピング画像に及ぼす影響
Note (General)Optical mapping has been applied to image brain activation two-dimensionally along the head surface by detecting the intensity changes of light that passes through the brain. In optical mapping for imaging brain activity, it is assumed that the head tissue is spatially homogeneous and temporally invariable except the activated region in the brain. However, in the superficial layers above the brain, the tissues are inhomogeneous and vary hemodynamically. Furthermore, light propagation and the optical pathlength inside the head are highly dependent on the anatomy and physiology in the head. In particular, the spatial variations in the thickness of skull and cerebrospinal fluid (CSF) layers, the existence of the blood vessels and the hemodynamic changes in the superficial layers such as the CSF and skin layers would have significant influences on light propagation and would result in the difference in the mapping images. However, itis difficult to know these influences by in vivo experiments. The aim of this study is to investigate these influences by numerical and experimental methods. Three-dimensional head models are used to simulate light propagation in the head by solving the photon diffusion equation using the finite element method (FEM), and the optical mapping images are constructed from the simulated measurement data. Tissue-mimicking phantoms with spatially varying thickness and changeable optical properties of head layers were also developed and multi-channel near-infrared spectroscopy (NIRS) experiments were performed on the dynamic phantoms. In the numerical simulations and phantom experiments, the changes in the optical densities (ΔOD) due to activated regions are obtained to construct the mapping images, and the light path probability distributions between one pair of source and detector are calculated to show the sensitivity of the tissue regions to the mapping images. As theresults, the influences of (1) the spatial variations of the skull and CSF layers and (2) the blood volume changes in the skin and CSF layers on the mapping images of brain activities are investigated quantitatively. The optical mapping for the single or multiple activated regions and the effects of the position of the activated regions relative to theprobe arrays on mapping images are also discussed. The quantitative results about the influences of the superficial layers in this study provide information for compensating the optical mapping images among different individuals or different head regions in an individual. In vivo experiments considering the influences of structural and hemodynamic differences in the superficial layers onoptical mapping remain as a future subject.
2013
Collection (particular)国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
Date Accepted (W3CDTF)2016-07-07T04:28:02+09:00
Data Provider (Database)国立国会図書館 : 国立国会図書館デジタルコレクション