Characterization of white matter changes along fibers by automated fiber quantification in the early stages of Alzheimer's disease
Characterization of white matter changes along fibers by automated fiber quantification in the early stages of Alzheimer's disease
复制标题
在阿尔茨海默病的早期阶段，通过自动纤维定量来表征沿纤维的白质变化
DOI：
10.1016/j.nicl.2019.101723
复制
发表时间：
2019-01-01
影响因子：
4.2
通讯作者：
Zhang, Bing
中科院分区：
文献类型：
--
作者：
Xin Zhang;Sun, Yu;Zhang, Bing
轻度认知障碍(MCI)和阿尔茨海默病(AD)患者的脑白质纤维束具有在未受影响的受试者中罕见的异常。白质完整性定位特性的理想算法可以揭示组织特性在每一束上的变化，而以往的研究只检测到每根纤维的平均DTI参数。这项研究的目的是调查这些神经纤维束的异常是否局限于神经束的特定区域或散布在整个神经束中，并分析哪些被检查的纤维束与阿尔茨海默病的早期阶段有关。在这项研究中，我们使用VBA、TBSS以及AFQ对25例CE患者、29例MCI患者和34例正常对照(NC)的白质纤维损害进行了综合研究。我们提取了两个纤维束的轮廓，即分数各向异性(FA)和平均弥散率(MD)，以评估沿20个纤维束的100个位置的白质完整性，然后我们验证了来自ADNI队列的27名CE患者、21名MCI患者和22名NC的结果。此外，我们在我们的队列中将AFQ与VBA和TBSS进行了比较。与正常对照组相比，AD患者在检查的纤维束中有25%(5/20)的FA普遍减少，65%(13/20)的MD增加。MCI患者5%(1/20)的受检纤维束(右侧扣带回)局部FA减少，5%(1/20)的受检纤维束(左侧弓状束)MD增加。在这些改变束中，只有右侧扣带回显示MCI中髓鞘或/和纤维轴突的广泛破坏和AD的加重，这一结果与平均FA/MD变化和点状法和TBSS的FA变化相支持。ADNI队列的AFQ发现与我们的队列有一些相似之处，特别是在AD和NC之间MD分布的逐点比较上。此外，不同神经纤维束的白质异常模式也不同，例如，MCI和AD患者右侧扣带回中部的FA减少相似，而右侧扣带回的前部未受到损害。而MCI患者左侧弓状束MD隆起位于纤维的颞部，AD患者则扩大至纤维的颞部和中部。因此，AFQ可能是VBA和TBSS的替代补充方法，并可能为MCI的白质变性及其与AD的关系提供新的见解。
Brain white matter fiber bundles in patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD) have abnormalities not usually seen in unaffected subjects. Ideal algorithm of the localization-specific properties in white matter integrity might reveal the changes of tissue properties varying along each tract, while previous studies only detected the mean DTI parameters of each fiber. The aim of this study was to investigate whether these abnormalities of nerve fiber tracts are localized to specific regions of the tracts or spread throughout and to analyze which of the examined fiber tracts are involved in the early stages of Alzheimer's disease. In this study, we utilized VBA, TBSS as well as AFQ together to comprehensively investigate the white matter fiber impairment on 25 CE patients, 29 MCI patients and 34 normal control (NC) subjects. Two tract profiles, fractional anisotropy (FA) and mean diffusivity (MD), were extracted to evaluate the white matter integrity at 100 locations along each of 20 fiber tracts and then we validated the results with 27 CE patients, 21 MCI patients and 22 NC from the ADNI cohort. Also, we compare the AFQ with VBA and TBSS in our cohort. In comparison with NC, AD patients showed widespread FA reduction in 25% (5 /20) and MD increase in 65%(13/20) of the examined fiber tracts. The MCI patients showed a regional FA reduction in 5% (1/20) of the examined fiber tracts (right cingulum cingulate) and MD increase in 5%(1/20) of the examined fiber tracts (left arcuate fasciculus). Among these changed tracts, only the right cingulum cingulate showed widespread disruption of myelin or/and fiber axons in MCI and aggravated deterioration in AD, findings supported by FA/MD changes both by the mean and FA changes by point wise methods and TBSS. And the AFQ findings from ADNI cohort showed some similarity with our cohort, especially in the pointwise comparison of MD profiles between AD vs NC. Furthermore, the pattern of white matter abnormalities was different across neuronal fiber tracts; for example, the MCI and AD patients showed similar FA reduction in the middle part of the right cingulum cingulate, and the anterior part were not damaged. However, the left arcuate fasciculus showed MD elevation located at the temporal part of the fibers in the MCI patients and expanding to the temporal and middle part of the fibers in AD patients. So, the AFQ may be an alternative complementary method of VBA and TBSS, and may provide new insights into white matter degeneration in MCI and its association with AD.