皮层下血管型轻度认知功能障碍的多模态磁共振研究

发布时间：2018-04-18 01:29

本文选题：轻度认知功能障碍 + 基于体素的形态学测量　；参考：《哈尔滨医科大学》2012年硕士论文

【摘要】：轻度认知功能障碍（Mild cognitive impairment, MCI）指介于正常衰老和痴呆之间的一种过渡状态，由于其转化的异质性，可进一步分为不同亚型，主要分为遗忘型和非遗忘性两种。由于发病率和认识的局限，既往对MCI的研究多集中于遗忘亚型。近年来，随着神经学家对MCI的不断认识，非遗忘性MCI尤其是其中的皮层下血管型MCI（Subcortical Vascular MCI, svMCI）受到更广泛的关注。研究表明svMCI可进一步转化为皮层下血管型痴呆，是最常见的一种血管型痴呆。MCI不仅具有转化成相应痴呆的趋势，，同时也有一定的可逆性。所以对svMCI患者的脑的结构与功能异常进行研究，能够为进一步认识svMCI的病理生理学机制提供新的角度。随着核磁共振（Magnetic Resonance Image, MRI）技术的发展，新技术的提出如结构MRI和静息态功能MRI的出现，为脑研究提供了在活体对脑进行结构与功能研究的机会。结构MRI能够提供脑组织的丰富信息，尤其是在疾病状态下，脑的萎缩或结构改变。近年来，静息态功能MRI作为一种有效、无侵入性的方法被用于研究人脑在不执行特定任务时的自发活动。这种基于血样水平依赖信号的低频自发活动的研究能够帮助认识人脑自发活动机制。不仅如此，静息态MRI也可用于对疾病的研究中。本研究结合结构MRI和静息态功能磁共振技术，对svMCI的脑结构和自发脑活动进行研究。功能方面，我们使用低频波幅（Amplitudeof Low-Frequency Fluctuation, ALFF）的分析方法。脑血样依赖信号的低频自发波动反映局部脑的自发活动，该已应用于不同疾病的研究中，如遗忘型MCI、阿尔茨海默氏病、精神分裂以及颞叶癫痫等，且具有相当的敏感性。结构方面，我们使用基于体素的形态学研究方法（Voxel-Based Morphometry, VBM）对全脑灰质体积进行分析，进一步的我们也探讨了svMCI功能改变与结构异常之间的关系。本研究分别采集了26个svMCI患者和28个正常对照的功能和结构MRI数据并对其分析。结果发现，与正常人相比，svMCI患者的低频脑活动异常区主要位于默认网络（Default Mode Network, DMN），活动减低的部位位于DMN的前部（如内侧前额叶），而自发活动的脑区则位于DMN的后部（如扣带回后部及楔叶、顶下小叶）。结构方面，与正常对照相比，svMCI患者有广泛的皮层萎缩，主要在额叶的额上回、额中回，颞叶的颞上回、颞中回和海马等脑区。更重要的是，在皮层下灰质也有所发现，如丘脑和尾状核。最后，经过对结构异常进行统计学处理，控制结构改变后协变量，功能结果的差异不大，有此可见功能的异常并不能完全由结构的改变来解释。综上所述，本研究发现了svMCI患者相比正常人在功能和结构影像上的广泛异常，对进一步理解其病理生理学机制具有一定的科学意义。
[Abstract]:Mild cognitive impairment (mild cognitive impairment) refers to a transition state between normal aging and dementia. Due to the heterogeneity of its transformation, it can be further divided into two subtypes, amnesia and non-amnesia.Due to the limitation of morbidity and cognition, previous studies on MCI have focused on forgotten subtypes.In recent years, with the increasing recognition of MCI by neuroscientists, more and more attention has been paid to non-forgotten MCI, especially the subcortical vascular type MCI(Subcortical Vascular MCI (svMCI).The results show that svMCI can be further transformed into subcortical vascular dementia, which is the most common type of vascular dementia. MCI not only has the tendency of converting into corresponding dementia, but also has certain reversibility.Therefore, the study of abnormal brain structure and function in patients with svMCI can provide a new perspective for further understanding the pathophysiological mechanism of svMCI.With the development of magnetic Resonance image (MRI) technology, the emergence of new techniques such as structural MRI and resting functional MRI provides an opportunity for the study of brain structure and function in vivo.Structural MRI can provide abundant information about brain tissue, especially in the condition of disease, brain atrophy or structural change.In recent years, the resting function MRI has been used as an effective and non-invasive method to study the spontaneous activity of human brain without performing specific tasks.The study of low frequency spontaneous activity based on blood level dependent signal can help to understand the mechanism of human brain spontaneous activity.Moreover, resting MRI can also be used in the study of disease.In this study, the brain structure and spontaneous brain activity of svMCI were studied by structural MRI and resting functional magnetic resonance technique.In terms of function, we use the method of low frequency amplitude Amplitudeof Low-Frequency Fluctuation (ALFF).The low frequency spontaneous fluctuation of cerebral blood dependent signal reflects the spontaneous activity of the local brain. It has been applied to the study of different diseases, such as amnesia MCI, Alzheimer's disease, schizophrenia and temporal lobe epilepsy.In terms of structure, we used Voxel-Based morphometry (VBM) to analyze the whole brain gray matter volume. Furthermore, we also discussed the relationship between svMCI functional changes and structural abnormalities.Functional and structural MRI data of 26 svMCI patients and 28 normal controls were collected and analyzed in this study.And it turns out,The low frequency abnormal areas of brain activity were mainly located in the default network, default Mode Network, DMNs, and the areas of decreased activity were located in the anterior part of DMN (such as medial prefrontal lobe), while the spontaneous regions of the brain were located in the posterior part of DMN (such as posterior cingulate gyrus and cuneiform lobe).The lower apex of the lobules.Compared with the normal controls, the patients with svMCI had extensive cortical atrophy, mainly in the superior frontal gyrus, middle frontal gyrus, superior temporal gyrus, middle temporal gyrus and hippocampus.More importantly, it is also found in subcortical gray matter, such as the thalamus and caudate nucleus.Finally, after the statistical processing of the structural anomalies, the covariables after the control structure changes, the difference of the functional results is not significant, so the functional anomalies can not be fully explained by the structural changes.To sum up, this study found extensive abnormalities in functional and structural imaging of svMCI patients compared with normal persons, which is of scientific significance for further understanding its pathophysiological mechanism.
【学位授予单位】：哈尔滨医科大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R749.16

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