Age-related changes in gray and white matter microstucture of patients with macular dystrophies and healthy controls as revealed by DTI.
Age-related changes in gray and white matter microstucture of patients with macular dystrophies and healthy controls as revealed by DTI.
复制标题
DTI 显示黄斑营养不良患者和健康对照者灰质和白质微观结构与年龄相关的变化
DOI：
10.1167/15.12.987
复制
发表时间：
2015
影响因子：
1.8
通讯作者：
Greenlee
中科院分区：
文献类型：
--
作者：
Greenlee
已有研究表明，黄斑变性导致的中央视力丧失不仅影响视觉通路的功能加工，而且影响视觉通路的宏观结构。特别是，磁共振成像（MRI）显示黄斑变性患者在代表中央视野的胼胝体沟部分的灰质和白质体积减少。然而，这些由部分视力丧失引起的宏观结构改变的基础尚不清楚。基于MRI的弥散张量成像（DTI）是一种可以推断脑组织微观结构的技术。在这里，25例遗传性黄斑变性患者和13例年龄相关性黄斑变性患者以及相同数量的年龄匹配的健康对照（年龄范围从19岁到85岁）进行了DTI检查。患者和对照组比较了几种基于扩散的定量指标，包括分数各向异性（FA）、平均扩散率（MD）、轴向扩散率（AD）和径向扩散率（RD）。采用基于表面的分析方法。在健康人群中，随着年龄的增长，枕叶内侧皮层、扣带皮层、颞叶皮层、岛叶皮层和额叶皮层的弥散性增加。然而，AD和RD之间的分离在几个大脑区域被观察到：RD的年龄相关增加主要在枕叶内侧皮层的白质中观察到，而AD的年龄相关增加主要在颞叶皮层的灰质中观察到。与年龄匹配的健康对照相比，年轻而非老年的视力丧失患者在后钙槽和额叶下皮质的两个不同区域显示RD增加。没有观察到AD的减少。这一发现表明，在视力丧失的患者中，传入视觉通路的纤维连接仍然保留。然而，视觉皮层的白质微观结构可能受到局部连通性或轴突外结构变化的影响。
Previous research has shown that loss of central vision resulting from macular degeneration not only affects functional processing but also the macroscopic structure of the visual pathway. In particular, magnetic resonance imaging (MRI) showed volumetric reductions of the gray and white matter of patients with macular degeneration in portions of the calcarine sulcus that represent the central visual field. However, the basis of these macrostructural alterations due to partial vision loss is still unclear. Diffusion tensor imaging (DTI) based on MRI is a technique that allows inferences about the microstructure of brain tissue. Here, 25 patients with hereditary and 13 patients with age-related macular degeneration and an equal number of age-matched healthy controls (age range from 19 to 85 years) were examined with DTI. Patients and controls were compared on several diffusion-based quantitative indices including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD). A surface-based analysis approach was adopted. In healthy people, diffusivity increased with age in the medial occipital cortex, the cingulate cortex, the temporal cortex, the insular, and the frontal cortex. However, dissociations between AD and RD were observed in several brain regions: Age-related increases of RD were primarily observed in the white matter of the medial occipital cortex, whereas age-related increases of AD were primarily observed in the gray matter of the temporal cortex. Compared to age-matched healthy controls, young but not elderly patients with vision loss showed increased RD in two distinct regions of the posterior calcarine sulcus and the inferior frontal cortex. No reduction in AD was observed. This finding suggests that fiber connections of afferent visual pathways are still preserved in patients with vision loss. However, the white matter microstructure of the visual cortex may be affected by changes in local connectivity or the extra-axonal structure.