弥散张量成像数据处理方法的研究与应用

【作者】 张静娜；

【导师】 陈华富；

【作者基本信息】 电子科技大学 ， 生物医学工程， 2010， 硕士

【摘要】 弥散张量成像(diffusion tensor imaging,DTI)是一种新的磁共振成像技术,具有无损伤的特点。它不但可以在三维空间内定量分析组织内水分子的弥散运动,而且可以利用组织内水分子弥散呈现的各向异性的特征进行成像。近年来,弥散张量成像已初步应用于临床研究,并成为一种对脑白质疾病,脑血管疾病及精神障碍性疾病进行临床诊断的新方法。本论文利用弥散张量成像技术对中颞叶癫痫和社交焦虑障碍这两种疾病进行了初步的影像学研究。中颞叶癫痫(Medial temporal lobe epilepsy,mTLE)是一种常见的局部性癫痫,发病期间会发放异常电位。为了探测mTLE病人的大脑白质是否存在弥散特性和白质完整性的异常,论文通过基于体素的方法(voxel-based analysis,VBA)对mTLE病人和正常对照组的弥散张量成像产生的弥散参数和白质密度指数进行了分析研究。结果发现mTLE病人的双侧海马的弥散特性出现异常,这与以前的研究结果一致。同时我们还进一步的发现双侧海马的白质完整性的异常,以及双侧海马的参数之间相关性的消失。这些结果表明mTLE病人的海马区域结构连接的异常,这对mTLE病人癫痫发作机制的研究具有重要的参考价值。以前的社交焦虑症(Social anxiety disorder,SAD)研究表明,SAD患者存在一些大脑认知功能方面的障碍。结构是功能的载体,为了研究SAD患者是否存在大脑结构连接异常,论文通过弥散张量成像方法对社交焦虑症患者进行了大脑结构网络的研究。首先通过对白质纤维束追踪、标准大脑模板到原始大脑空间的反投、大脑结构网络重建等计算方法进行分析,找出了大脑结构网络分析的算法。然后把算法用于处理SAD患者的数据。研究结果发现SAD患者的左脑的颞叶和角回、颞叶和脑岛、颞叶和海马、额叶和脑岛、额叶和前扣带、楔前叶和海马旁回、楔前叶和顶上叶,以及右脑的颞叶和角回、颞叶和枕叶、额叶和脑岛、中央前回和缘上回这些区域的结构连接比正常被试弱。这些结果与以前脑影像学研究结果基本一致,这表明SAD患者的多个脑区之间的神经纤维连接存在异常,这对研究社交焦虑障碍患者的神经机制具有很重要的参考价值。更多还原

【Abstract】 Diffusion tensor imaging(DTI) is a new noninvasive magnetic resonance imaging(MRI)technique. DTI not only can provide quantitative analysis of the diffusion of water molecules in a three-dimensional space, but also can use the anisotropic characteristics presented by the diffusion of water molecules to image. In recent years, DTI has been used in clinical research, and become a kind of new methods in clinical diagnosis of the white matter disease, cerebrovascular disease and mental disorder. In this study, DTI was mainly used to investigate the radiological manifestation of bilateral mesial temporal lobe epilepsy and social anxiety disorder.Mesial temporal lobe epilepsy (mTLE) is one of the most common focal epilepsy, the patient will grant exception potential during an attack. To investigate changes in fiber integrity along with diffusivity in the bilateral mTLE patients, we study the diffusion parameters and fiber density index (FDI) of DTI by the voxel-based analysis (VBA) method. The results show that there were diffusion abnormalities in the bilateral hippocampus in patients. The results were in line with previous studies. Furthermore, we found the abnormalities of fiber integrity in bilateral hippocampus and lose of the relativity among the parameters. The results demonstrate the abnormality of structural connection in hippocampus in the bilateral mTLE patients, which provides important reference value for the study of the pathogenesis of epilepsy.The previous study of social anxiety disorder (SAD) showed that the patients of SAD had cognitive dysfunction. Structure is the carrier of the function, in order to explore whether there are anomalous structural connections in SAD, we studied the structural network of SAD by DTI. Through the study of the methods in white matter fiber tracking, back-projection of the standard brain template to the original space, the reconstruction of the brain structural network, we got the algorithm of the analysis of the structural network. And then we implement the algorithm at DTI data of SAD. The results show that there were reduce of the structural connections among temporal lobe and angular gyrus, temporal lobe and insula, temporal lobe and hippocampus, frontal lobe and insula, frontal lobe and anterior cingulated cortex, precuneus and parahippocampal gyrus, precuneus and superior parietal lobe in the left brain, and among temporal lobe and angular, temporal lobe and occipital lobe, frontal lobe and insula, precentral gyrus and supramarginal gyrus in the right brain. The regions involved in these reduced structural connections are consistent with the results reported in the previous studies about SAD, which indicates that there are abnormal nerve fiber connections among multiple brain regions in patients of SAD. It has important reference value in the study of neural mechanisms of SAD.更多还原