脑白质高信号的磁共振影像学研究

发布时间：2018-02-12 01:42

本文关键词： 脑白质高信号磁敏感加权成像体素内不相干运动弥散张量成像深髓静脉灌注认知改变　出处：《浙江大学》2017年博士论文　论文类型：学位论文

【摘要】：脑白质高信号(white matter hyperintensities,WMH)是表现为在磁共振T2加权像或T2液体衰减反转恢复序列上,双侧侧脑室周围或皮质下白质多发的点状、斑片状或融合性高信号。有研究表明90%以上的老年人存在WMH。WMH过去被认为是一种与年龄相关的正常生理改变,但近年的研究表明,WMH是卒中、痴呆、抑郁等疾病发生的高危风险因素,研究WMH的发生发展机制及其与脑功能结构异常、行为功能损害的关系具有重要临床价值。本研究主要基于多模态磁共振成像(MRI)技术,采用磁敏感加权成像、弥散张量成像、体素内不相干运动等方法,探索WMH的发生机制、以及WMH在认知功能下降中的作用机制。主要内容包括以下三部分:第一部分脑白质高信号发生的静脉源性机制研究研究显示大脑静脉胶原纤维化所致静脉回流障碍与WMH有关,但缺乏客观的在体研究证据。我们通过磁共振磁敏感成像技术量化脑深髓静脉扩张或缺血与WMH严重程度的相关性。本研究回顾分析了 158例WMH患者和50例对照组患者的临床和检验数据,在3TMRI上以磁敏感加权成像方法测量了深髓静脉体素数量和用T2 Flair测量WMH组织体积(作为WMH严重度的指标)。随后,对体素数量和WMH体积的相关性进行线性回归分析和Pearson相关性分析。WMH患者的深髓静脉体素数量明显高于对照组。增加的深髓静脉体素数量同时与全脑WMH体积和对年龄和病灶数量因素调整后的局部的WMH体积独立相关。本研究显示脑深部静脉血流不足或缺血在WMH的发病机理中发挥重要作用,作为WMH患者的预测以及对治疗效果监测有积极意义。第二部分脑白质高信号微循环和微结构改变和认知功能减退相关性的研究WMH与认知功能减退有关,但目前对WMH的认知功能减退患者的大脑微循环和微结构改变知之甚少。本研究拟采用体素不相干运动(Intravoxel Incoherent Motion,IVIM)技术研究WMH微循环和微结构改变及其与认知功能的相关性。本研究共招募32例WMH患者入组本研究。研究比较了 WMH区域(包含室周白质高信号 periventricular WMHs,PWMHs 和深部白质高信号 deep WMHs,DWMHs)与周边正常白质的IVIM模型重建的快速弥散系数(D*)、灌注系数(f)和慢速弥散系数(D)。采用多变量线性分析确定与认知功能相关的独立因素。认知功能情况采用简易精神状态检查表进行评估。研究结果发现相对于正常脑白质组织,WMH组织D*显著降低,f值显著升高,D值显著升高。只有PWMH中f值是与认知功能MMSE评分独立相关。本研究提示WMH患者快速弥散系数D*降低,而慢速弥散系数D增加;研究还发现PWMHs灌注系数f增高与更佳的认知功能有关,此发现为我们理解WMH患者认知功能减退提供了病理生理基础。第三部分脑白质高信号全脑纤维束损害特征的MRI研究WMH发生的部位、体积与功能障碍的发生存在着一定程度的对应关系,目前仍然缺乏针对WMH病变过程中是否存在某些纤维束特异性受损导致不同功能损害,以及不同纤维束之间受损严重程度比较的研究。本研究连续招募125例WMH患者和74例正常对照者。采用约翰霍普金斯大学Brain Mapping的纤维束模板,观察WMH患者全脑不同纤维束的DTI参数的改变。研究结果显示WMH弥散地影响全脑的纤维束结构,所有纤维束均出现FA值下降,MD值升高;其影响范围远大于T2FLAIR上所观察到的高信号区域;而不同纤维束在病程中受损的情况并不相同,上纵束、额枕束和丘脑前放射等纤维束的结构受到了更加严重的损害,未来的研究应该对这些部位的WMH更易导致纤维束受损加以考虑。
[Abstract]:Cerebral white matter hyperintensities (white matter, hyperintensities, WMH) is showed in T2 weighted magnetic resonance imaging or T2 flair, bilateral periventricular and subcortical white matter in multiple punctate, patchy or diffuse high signal. Studies have shown that more than 90% years old people are WMH.WMH in the past is considered to be a normal physiological age-related changes, but recent studies show that WMH is a high risk factor of stroke, dementia, depression and other diseases, the mechanism of the occurrence and development of WMH and its structure and brain function abnormality, has important clinical value in behavior impairment. This study is mainly based on multi modality magnetic magnetic resonance imaging (MRI) technique, using susceptibility weighted imaging, diffusion tensor imaging, intravoxel incoherent motion and other methods, to explore the mechanism of WMH, and the mechanism of WMH in cognitive decline in the main content. The research includes the following three parts: the first part vein source mechanism of cerebral white matter hyperintensities occurred showed cerebral vein collagen fibrosis caused by venous reflux disorder associated with WMH, but the lack of objective evidence. We study in vivo by magnetic resonance imaging to quantify the susceptibility of deep brain ischemia or expansion of medullary veins and the severity of WMH correlation this study. A retrospective analysis of 158 cases of WMH patients and 50 control groups of patients with clinical and laboratory data, on 3TMRI susceptibility weighted imaging method for measuring deep medullary veins voxels with T2 and Flair WMH volume measurement organization (as WMH severity index) were analyzed. Then, linear regression analysis the correlation between Pearson and.WMH deep medullary veins in number of patients was significantly higher than the control group on the voxel correlation quantity and volume of WMH. Deep medullary veins increase in number and whole brain volume and WMH To adjust the number of independent related factors of local lesion age and the volume of the WMH. This study shows that the deep cerebral venous blood deficiency or ischemia play an important role in the pathogenesis of WMH, as predicted in WMH patients and to monitor treatment has a positive meaning. The second part of the brain white matter hyperintensities and micro structure change and microcirculation the cognitive dysfunction of WMH and cognitive function correlation loss related to, but the cognitive function of WMH patients with impaired cerebral microcirculation and micro structure change is poorly understood. In this study we used voxel incoherent motion (Intravoxel Incoherent, Motion, IVIM) WMH technology research of microcirculation and micro structure changes and their relationship with cognitive function. This study recruited 32 patients with WMH were enrolled in this study. The research and comparison of the WMH region (including periventricular white matter hyperintensities on periventricular WMHs, PWMHs and deep white matter Deep signal WMHs, DWMHs) fast diffusion coefficient IVIM model reconstruction and the surrounding normal white matter (D*), the perfusion coefficient (f) and slow diffusion coefficient (D). Analysis using multivariate linear independent factors associated with cognitive function. The cognitive function with mini mental state examination of assessment. Results compared with normal brain white matter tissue, WMH tissue D* decreased significantly, f increased and D values increased significantly. Only in the PWMH F value is independently associated with cognitive function score of MMSE. This study suggests that WMH patients with rapid diffusion coefficient D* decreased, while the slow diffusion coefficient D increases; the study also found that PWMHs perfusion coefficient f correlated with cognitive function better, the findings of cognitive function in patients with WMH provides the pathophysiological basis of loss for us to understand the WMH features of MRI parts. The third part of the brain white matter hyperintensities brain fiber bundle damage body Product and dysfunction is related to a certain extent, there is still a lack of specificity for whether certain fiber bundle damage lead to different functional damage WMH lesions, and between different fiber bundle injury severity of comparison. The study recruited 125 consecutive patients with WMH and 74 normal controls. The fiber bundle template the Johns Hopkins University Brain Mapping, observe the DTI parameters of the whole brain of different fiber bundles with WMH changes. Research results show that the effect of whole brain fiber bundle structure of WMH dispersion, all fiber bundles showed FA decreased, MD value increased; the range of influence is far greater than the high signal area of T2FLAIR on the observed difference; the fiber bundle damage in the course of the disease is not the same, superior longitudinal fasciculus, fronto occipital fasciculus and anterior thalamic radiation structure of fiber bundle has been more serious damage in the future. It should be considered that the WMH of these parts should be more vulnerable to the damage of the fiber bundles.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：R445.2;R741

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