Hanyu H, Asano T, Ogawa K, Takasaki M, Shindo H, Kakizaki D, Abe K
Department of Geriatric Medicine, Tokyo Medical College, Japan.
No To Shinkei. 1997 Apr;49(4):331-6.
To investigate age-related changes of diffusional anisotropy in the cerebral white matter, we performed diffusion-weighted MRI studies in 21 normal subjects aged 25 to 96 years. The anisotropic rations (ARs), defined as the apparent diffusion coefficients perpendicular to the nerve fibers to those parallel to the nerve fibers, were significantly higher in elderly than in young subjects in the anterior and posterior white matter surrounding the lateral ventricle. Moreover, significant correlation between age and AR was found in the anterior white matter. The ventricular index (VI) measured on MRI, as a quantitative indicator of brain atrophy, was significantly higher in elderly than younger subjects, and significantly correlated with AR in the anterior white matter. Multiple regression analysis demonstrated that the VI showed the highest correlation for AR. On the other hand, there was no significant correlations between ARs in the corpus callosum and age. These results suggest that morphological changes in the myelin and axon in the white matter occur in elderly normal subjects, probably due to neuronal loss with aging.
为研究脑白质扩散各向异性的年龄相关性变化，我们对21名年龄在25至96岁的正常受试者进行了扩散加权磁共振成像研究。各向异性比率（ARs）定义为垂直于神经纤维的表观扩散系数与平行于神经纤维的表观扩散系数之比，在侧脑室周围的前、后白质中，老年受试者的该比率显著高于年轻受试者。此外，在前白质中发现年龄与AR之间存在显著相关性。磁共振成像测量的脑室指数（VI）作为脑萎缩的定量指标，老年受试者显著高于年轻受试者，且与前白质中的AR显著相关。多元回归分析表明，VI与AR的相关性最高。另一方面，胼胝体中的ARs与年龄之间无显著相关性。这些结果表明，老年正常受试者白质中的髓鞘和轴突发生了形态学变化，这可能是由于衰老导致神经元丢失所致。
