| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2002: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2001: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
Diffusion-tensor (DT) MR imaging has been proposed as an attractive noninvasive tool for evaluating microstructural and physiological states in biological tissues by measuring the diffusion process of water molecules. Random displacements of water molecules (i.e. diffusion) are modified by stuctural and physiological factors in a medium. In brain white matter, diffusivity of water molecules is not the same in all directions of three dimensional space and is anisotropic at an imaging voxel scale due to its characteristic ordered microscopic and macroscopic features such as myelin sheath, axon, and fiber tract. The diffusion process is graphically expressed as an ellipsoid. By estimating properties of the ellipsoid, useful quantitative physiological and structural (including histopathological) information about white matter can be obtained
During late embryonic and early postnatal stage, high anisotropy is observed in rat brain gray matter. By later postnatal ages, the anisotropy, decreases. This anisotropy of the cortical gray matter is low in adult rats. By comparison between the anisotropic changes and the histopathological changes in the rat cortical gray matter from late embryonic stage to late postnatal stage, determination factors and their contribution to anisotropic diffusion process can be revealed. This seems to be essential for evaluating information derived from diffusion tensor MR imaging
This study includes development of rat brain diffusion MR in vitro imaging technique, creation of diffusion tensor calculation and mapping tools, and estimation of immunohistochemical featres of Sprague-Dawley rat brain cortex, to evaluate relationship between the anisotropic changes and the histopathological changes in the rat cortical gray matter from late embryonic stage to late postnatal stage
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