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

项目摘要/摘要 该项目的总体目标是提供一个自动扩散图像分析工具，以 在结合磁共振快速评估扩散图像的临床环境中使用 体积图像和报告基于扩散的微结构参数源自 分段解剖定位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-淀粉样沉积和神经原纤维缠结 先于神经元丢失和认知功能衰退。因此，定量容积法和测量 神经功能作为潜在的生物影像标志物已被广泛研究。那里有 越来越多的证据表明阿尔茨海默氏症患者的大脑微结构发生了变化 神经小体的体积和功能变化。虽然扩散成像已经被 在涉及特定白质通路的疾病中有效地使用，最近在 扩散成像技术，特别是多室模型 量化微结构变化现在能够有效地使用扩散成像 阿尔茨海默氏症。限制谱成像(RSI)是一种先进的扩散成像技术 方法，目前可用于主要制造商的磁共振扫描仪，这些制造商具有 获取多层扩散成像的能力。阿尔茨海默病的最新研究进展 采用扩散技术的患者报告多发性白色病变的扩散各向异性降低。 物质束以及灰质结构中弥散增加。微观结构变化 由于轴突和树突的病理，将反映在弥漫性措施。进阶 对轴突密度和方向敏感的扩散方法最适合于 阿尔茨海默病认知功能减退前的神经病理改变 病人。事实上，PET研究测量的牛磺酸沉淀物与 本文报道了用先进的扩散技术测量轴突密度指数。曾经有过 此外，也有证据表明阿尔茨海默病影响的脑区有更高的轴突分散 弥散张量成像所见。与认知测量和扩散的相关性 在一组阿尔茨海默病患者中也报告了参数。最近的研究表明 脑脊液中β-淀粉样蛋白和tau水平的异常与脑血管疾病的广泛改变相关 阿尔茨海默病患者脑白质的微结构。自证监会采取措施以来 是公认的AD病理、体内和非侵入性确定的扩散的生物标志物 参数可以传达与AD相关的大脑变化，并预测未来的认知能力下降。

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.