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Thesis Advisor刘勇
Degree Grantor中国科学院大学
Place of Conferral中国科学院自动化研究所
Degree Name工学硕士
Degree Discipline计算机技术
Keyword轻度认知障碍 白质高信号 动脉质子自旋标记成像 脑血流量 ASL图像处理工具

白质高信号(White Matter Hyperintensities, WMH)指大脑白质部分出现的异常信号,是脑小血管病的一种重要的影像学表现,伴有WMH的老年人常常伴有记忆、语言、视空间、执行、计算和理解判断等认知功能的损害,是认知障碍和痴呆的高危人群

大量的研究表明WMH被试脑活动模式异常、脑血流量(Cerebral Blood Flow, CBF)降低并伴有脑结构的改变。基于功能磁共振影像发现WMH患者的功能网络异常广泛分布于额叶、颞叶、顶叶皮层中,而且在记忆和认知回路中存在部分反常的活跃区域。动脉质子自旋标记(Arterial Spin Labeling, ASL)成像技术是目前应用最为广泛的CBF数据的获取技术,可以反映CBF的变化情况。功能连接强度(Functional connectivity strength, FCS)是功能连接网络相关研究中的一个常用指标,可以反映大脑不同区域在神经活动中的一致性程度,而CBF代表着每100g组织每分钟流过的血液,可以刻画大脑活动活跃程度。CBF/FCS比被用来用于表征血管反应和大脑中的神经元活动之间的耦合性。本文主要关心的问题是寻找在伴随白质高信号的老年人群中FCSCBFCBF/FCS 有哪些异常模式及它们由于疾病导致的变化最明显的区域分布在哪些脑区。更进一步,探索这些异常模式是否与被试的认知、白质高信号的体积大小、白质高信号的空间位置有关。

为了回答上述问题,本研究纳入103例数据,其中健康对照组(Normal Controls, NC48人,存在WMH但没有认知损害的被试42人(WMH-nCI组)和伴有认知损害的被试(WMH-MCI组)13人,并从体素、不同尺度的脑图谱探索WMH和认知损害是否会影响FCSCBFCBF FCS的耦合关系是否会出现异常并定位出现显著差异的区域分布。研究发现WMH-nCIWMH-MCI组相对NC组均在下额叶、颞叶、楔前叶、扣带回及部分皮下核团出现显著的CBF衰减且WMH-MCI组的衰减范围大于WMH-nCI组,在额叶、枕叶、颞叶部分区域出现了FCS下降,在部分皮下核团出现了FCS上升。WMH-MCI组在颞叶、枕叶和皮下核团的部分区域出现CBF/FCS比值的显著下降。WMH-nCI在上额叶和上颞叶的小部分皮层出现了比值的上升。这些结果在不同尺度的脑图谱划分得到了验证。


Other Abstract

White matter hyperintensities (WMH), characterized by high signals on fluid-attenuated inversion recovery (FLAIR) and T2-weighted MR images, are commonly observed in older adults and are considered as one of the manifestations of cerebral small vessel disease. Convergent evidence suggests that WMH lead to cognitive decline and are associated with the risks of both vascular dementia and Alzheimer’s disease (AD)-related dementia. Elderly with WMH often suffer from damage on memory, language, visuospatial, execution, calculation, understanding or judgment skills, and have a high possibility to transform into cognitive impairment or dementia.

Many studies indicate that subjects with WMH have abnormal brain active patterns, declined CBF, and impaired brain structure. Studies on functional MRI find that brain functional network abnormalities of WMH patients distribute widely on the frontal, parietal, and temporal cortex. Also, some activated area exists in the circuits under memory and cognition. Arterial spin labeling (ASL) imaging is the most popular technique to achieve CBF data. Functional connectivity strength (FCS) can measure the correlation between neural activities in different brain regions, which is widely used in studies on functional connectivity networks. CBF can also measure neural activities by calculating how much blood passes through tissues. CBF/FCS ratio is used to characterize the coupling between vascular response and neural activity. The most important concerns in this paper are: what is the abnormal pattern on FCS, CBF, and CBF/FCS ratio in the elderly with WMH, where is the region with the most obvious changes. Furthermore, we tried to explore whether the abnormal pattern is related to cognition, the volume of WMH, and the spatial location of WMH.

To address these questions, data on 103 participants were used in this study, which divided into three groups: 48 normal controls (NC group), 42 WMH patients with no cognitive impairment (WMH-nCI group), and 13 MCI patients (WMH-MCI group). We also investigated whether WMH or cognitive impairment influences FCS or CBF, the coupling of CBF/FCS changes in these WMH subjects, if so, which brain region is affected. The results showed that the significant CBF decline in WMH-MCI or WMH-nCI groups in the inferior frontal lobe, temporal lobe, precuneus lobe, cingulate gyrus, and some subcortical nuclei compared with NC group, and the WMH-MCI group showed more decline areas than that in WMH-nCI group, in comparison to the NC. There is significant FCS decline in the frontal lobe, occipital lobe, and temporal lobe with significant FCS increase on some subcortical nuclei. Furthermore, the WMH-MCI group showed a significant CBF/FCS ratio decline in the temporal lobe, occipital lobe, and some subcortical nuclei, while the WMH-nCI group showed a significant increase in the superior frontal lobe and superior temporal lobe. These results are verified by different types of brain atlases.

Due to the absence of a simple and user-friendly ASL processing toolkit, we collected the codes to process ASL data, added user interface, and GUI window to provide a simple ASL toolkit which is easy to be installed and operated. This toolkit can be used to coregister, calculate, and correct the ASL data, which makes it convenient to perform the preprocessing ASL data.

Document Type学位论文
Recommended Citation
GB/T 7714
任家骥. 脑白质高信号人群脑血流异常研究及ASL分析系统构建[D]. 中国科学院自动化研究所. 中国科学院大学,2020.
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