白质
磁共振弥散成像
核磁共振
胼胝体
各向异性
医学
部分各向异性
有效扩散系数
扩散
扩散成像
纤维束成像
物理
磁共振成像
解剖
光学
放射科
热力学
作者
Carlo Pierpaoli,Peter Jezzard,Peter J. Basser,Alan Barnett,G Di Chiro
出处
期刊:Radiology
[Radiological Society of North America]
日期:1996-12-01
卷期号:201 (3): 637-648
被引量:2511
标识
DOI:10.1148/radiology.201.3.8939209
摘要
To assess intrinsic properties of water diffusion in normal human brain by using quantitative parameters derived from the diffusion tensor, D, which are insensitive to patient orientation.Maps of the principal diffusivities of D, of Trace(D), and of diffusion anisotropy indices were calculated in eight healthy adults from 31 multisection, interleaved echo-planar diffusion-weighted images acquired in about 25 minutes.No statistically significant differences in Trace(D) (approximately 2,100 x 10(-6) mm2/sec) were found within normal brain parenchyma, except in the cortex, where Trace(D) was higher. Diffusion anisotropy varied widely among different white matter regions, reflecting differences in fiber-tract architecture. In the corpus callosum and pyramidal tracts, the ratio of parallel to perpendicular diffusivities was approximately threefold higher than previously reported, and diffusion appeared cylindrically symmetric. However, in other white matter regions, particularly in the centrum semiovale, diffusion anisotropy was low, and cylindrical symmetry was not observed. Maps of parameters derived from D were also used to segment tissues based on their diffusion properties.A quantitative characterization of water diffusion in anisotropic, heterogeneously oriented tissues is clinically feasible. This should improve the neuroradiologic assessment of a variety of gray and white matter disorders.
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