Quantifying microstructural changes in Alzheimer's disease using Restriction Spectrum Imaging

项目总结/摘要 该项目的总体目标是提供一个自动化的扩散图像分析工具， 用于结合MR快速评价弥散图像的临床环境 体积图像和报告基于扩散的微观结构参数， 分割的解剖位置，以确定患者的阿尔茨海默病状态。 阿尔茨海默病的特征是β-淀粉样蛋白沉积和神经元缠结 神经元丧失和认知能力下降因此，定量容量法和测量 神经元功能作为潜在的生物成像标记物已被广泛研究。一直 此外，越来越多的证据表明阿尔茨海默氏症患者大脑的微观结构发生了变化， 神经元体的体积和功能变化。虽然扩散成像已经被 有效地用于涉及特定白色物质途径的疾病， 扩散成像技术，特别是多房室模型， 量化微结构变化现在使得扩散成像能够有效地用于 老年痴呆症限制谱成像（RSI）是一种先进的扩散成像技术， 方法，目前可以用于主要制造商的MR扫描仪， 获得多壳层扩散成像的能力。阿尔茨海默病的最新研究 采用扩散技术的患者报告了多个白色 物质束以及灰质结构中的扩散增加。显微结构变化 由于轴突和树突病理学，将反映在扩散措施。先进 对神经突密度和方向敏感的扩散方法最适合用于 阐明阿尔茨海默氏症认知能力下降前的神经病理学变化 患者事实上，通过PET研究测量的tau蛋白沉积和 报告了用先进扩散技术测量的神经突密度指数。有 也有证据表明，在阿尔茨海默病影响的大脑区域， 弥散张量成像表现。与认知测量和扩散的相关性 参数也报告了一组阿尔茨海默病患者。近年来的研究表明 CSF中β-淀粉样蛋白和tau水平的异常测量与广泛的改变相关， 白色物质微观结构遍布阿尔茨海默氏症患者的大脑。由于CSF措施 是AD病理学、体内和非侵入性测定扩散的公认生物标志物 参数可以传达AD相关的脑变化并预测未来的认知衰退。

Project Summary/Abstract The overall goal of this project is to deliver an automated diffusion image analysis tool to be used in a clinical setting that quickly evaluates the diffusion images in conjunction with MR volumetric images and reports diffusion-based microstructural parameters derived from segmented anatomical locations to determine Alzheimer’s disease status of patients. Alzheimer’s disease is characterized with β-amyloid deposits and neurofibrillary tangles preceding neuronal loss and cognitive decline. Hence quantitative volumetry and measures of neuronal function have been studied extensively as potential bioimaging markers. There has been increasing evidence of microstructural alterations in Alzheimer’s patients’ brains in addition to the volume and functional changes in neuronal bodies. While diffusion imaging has been used effectively in diseases involving specific white matter pathways, the recent advances in the diffusion imaging techniques particularly multi-compartmental models for successfully quantifying microstructural changes now enables the effective use of diffusion imaging in Alzheimer’s disease. Restriction Spectrum Imaging (RSI) is an advanced diffusion imaging method and currently can be used in MR scanners from major manufactures which have the capability to acquire multi-shell diffusion imaging. Recent studies of Alzheimer’s disease patients with diffusion techniques reported decreased diffusion anisotropy in multiple white matter tracts as well as increased diffusion in gray matter structures. Microstructural changes due to axonal and dendritic pathology, would reflect in diffusional measures. Advanced diffusion methods that are sensitive to neurite density and orientation are best qualified for elucidating the neuropathological changes preceding the cognitive decline in Alzheimer’s patients. Indeed, strong correlations between tau deposits measured by PET studies and neurite density index measured by advanced diffusion techniques were reported. There was also evidence of higher neurite dispersion in Alzheimer affected brain regions in addition to diffusion tensor imaging findings. Correlations with cognitive measures and diffusion parameters were also reported in a group of Alzheimer patients. Recent studies showed abnormal CSF measures of β-amyloid and tau levels associated with widespread alterations in white matter microstructures throughout the Alzheimer’s patients’ brains. Since CSF measures are well established biomarkers for AD pathology, in vivo and non-invasive determined diffusion parameters may convey AD related brain changes and predict future cognitive decline.