Diffusion tensor imaging in Alzheimer's disease and mild cognitive impairment
Diffusion tensor imaging in Alzheimer's disease and mild cognitive impairment
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DOI：
10.1155/2009/915041
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发表时间：
2009-01-01
影响因子：
2.8
通讯作者：
Murphy, C. M.
中科院分区：
文献类型：
--
作者：
Stebbins, G. T.;Murphy, C. M.
结构磁共振成像(MRI)对阿尔茨海默病和轻度认知障碍(MCI)的研究主要集中在海马体和内嗅皮层，即内侧颞叶的灰质结构。很少有研究调查AD或MCI患者脑白质的完整性。弥散张量成像(DTI)是一种MRI技术，可用于询问脑白质的微结构完整性。根据平移扩散增加(平均扩散系数：MD)和方向扩散减少(分数各向异性：FA)，可以评估脑白质的损伤。研究已确定AD和MCI患者所有脑叶以及内侧颞叶结构(包括海马体、内嗅皮层和海马旁白质)的MD增加和FA减少的区域。在AD和MCI中，白质完整性破坏的模式倾向于遵循从前到后的梯度，且在后部区域损害更大。最近的研究利用体素间的方向相似性来开发白质通路的模型，并使用这些模型来评估大脑间连接的完整性。特别关注的是海马区旁白质(包括穿支路)和后扣带。尽管许多研究已经发现了AD和MCI中白质受损的DTI指标，但其他研究未能发现这两组之间MD或FA的任何差异。论证了大规模复制研究的必要性。DTI是一种发展中的技术，其应用的进展应该为AD和MCI提供新的见解。
Structural magnetic resonance imaging (MRI) studies of Alzheimer's disease and mild cognitive impairment (MCI) have focused on the hippocampus and entorhinal cortex, gray matter structures in the medial temporal lobe. Few studies have investigated the integrity of white matter in patients with AD or MCI. Diffusion tensor imaging (DTI) is a MRI technique that allows for the interrogation of the microstructural integrity of white matter. Based on increases in translational diffusion (mean diffusivity: MD) and decreases directional diffusion (fractional anisotropy: FA) damage to white matter can be assessed. Studies have identified regions of increased MD and decreased FA in patients with AD and MCI in all lobes of the brain, as well as medial temporal lobe structures including the hippocampus, entorhinal cortex and parahippocampal white matter. The pattern of white matter integrity disruption tends to follow an anterior to posterior gradient with greater damage noted in posterior regions in AD and MCI. Recent studies have exploited inter-voxel directional similarities to develop models of white matter pathways, and have used these models to assess the integrity of inter-cerebral connections. Particular focus has been applied to the parahippocampal white matter (including the perforant path) and the posterior cingulum. Although many studies have found DTI indicators of impaired white matter in AD and MCI, other studies have failed to detect any differences in MD or FA between the groups.. demonstrating the need for large replicative studies. DTI is an evolving technique and advances in its application ought to provide new insights into AD and MCI.