Department of Radiology, Mayo Clinic, Rochester MN 55905, USA.
Neurology. 2010 Apr 20;74(16):1279-87. doi: 10.1212/WNL.0b013e3181d9edde.
To use diffusion tensor imaging (DTI) to assess gray matter and white matter tract diffusion in behavioral variant frontotemporal dementia (bvFTD), semantic dementia (SMD), and progressive nonfluent aphasia (PNFA).
This was a case-control study where 16 subjects with bvFTD, 7 with PNFA, and 4 with SMD were identified and matched by age and gender to 19 controls. All subjects had 3-T head MRI with a DTI sequence with diffusion encoding in 21 directions. Gray matter mean diffusivity (MD) was assessed using a region-of-interest (ROI) and voxel-level approach, and voxel-based morphometry was used to assess patterns of gray matter loss. White matter tract diffusivity (fractional anisotropy and radial diffusivity) was assessed by placing ROIs on tracts of interest.
In bvFTD, increased gray matter MD and gray matter loss were identified bilaterally throughout frontal and temporal lobes, with abnormal diffusivity observed in white matter tracts that connect to these regions. In SMD, gray matter loss and increased MD were identified predominantly in the left temporal lobe, with tract abnormalities observed in the inferior longitudinal fasciculus and uncinate fasciculus. In PNFA, gray matter loss and increased MD were observed in left inferior frontal lobe, insula, and supplemental motor area, with tract abnormalities observed in the superior longitudinal fasciculus.
The diffusivity of gray matter is increased in regions that are atrophic in frontotemporal dementia, suggesting disruption of the cytoarchitecture of remaining tissue. Furthermore, damage was identified in white matter tracts that interconnect these regions, supporting the hypothesis that these diseases involve different and specific brain networks.
使用弥散张量成像（DTI）评估行为变异型额颞叶痴呆（bvFTD）、语义性痴呆（SMD）和进行性非流利性失语症（PNFA）的灰质和白质束弥散。
这是一项病例对照研究，共纳入 16 例 bvFTD 患者、7 例 PNFA 患者和 4 例 SMD 患者，并按年龄和性别与 19 例对照进行匹配。所有患者均行 3-T 头部 MRI 检查，包括 DTI 序列，扩散编码方向为 21 个。使用感兴趣区（ROI）和体素水平方法评估灰质平均弥散度（MD），并采用基于体素的形态计量学方法评估灰质丢失模式。通过在感兴趣的白质束上放置 ROI 来评估白质束弥散（各向异性分数和径向弥散度）。
在 bvFTD 中，双侧额颞叶广泛存在灰质 MD 增加和灰质丢失，与这些区域相连的白质束也观察到异常弥散。在 SMD 中，主要在左侧颞叶发现灰质丢失和 MD 增加，观察到下纵束和钩束的异常。在 PNFA 中，左侧额下回、岛叶和辅助运动区观察到灰质丢失和 MD 增加，观察到上纵束的异常。
在额颞叶痴呆萎缩的区域，灰质弥散增加，提示剩余组织细胞结构受到破坏。此外，还观察到这些区域之间相互连接的白质束的损伤，支持这些疾病涉及不同和特定的脑网络的假说。
