White Matter Diffusion MRI in Children With Early Stroke

描述（由申请人提供）：对各种发育性脑障碍的研究的一个共同目标是了解对系统的损害如何影响大脑的后续发育。为了实现这一目标，我们研究了认知和大脑发育的儿童与单侧产前或围产期脑病变（PL）超过十年。我们的纵向，行为研究表明，PL的儿童有较轻的赤字比成人患者，在语言领域，病变部位和随后的赤字之间的映射不同于成人。儿童的轻度损伤和功能映射的不匹配表明神经基质的结构和组织发生了变化。为了检查完整大脑的宏观解剖结构，我们以前使用非侵入性磁共振成像（MRI）技术。神经解剖学脑发育的MRI分析显示病灶同侧和对侧半球的脑白色物质（WM）体积减少。WM衰减是区域特异性的，并且发生在通常会保持向损伤部位或通过损伤部位的投影的部位。因此，标准MRI技术限制了非侵入性检查WM束的机会。为了检查完整的WM纤维束早期中断后的结构变化，本研究将使用扩散加权成像（DWI）和定量分析技术。DWI对水分子的运动很敏感。在大脑中，细胞膜和髓鞘限制了水的运动，使得分子平行于轴突纤维而不是垂直于轴突纤维运动。因此，DWI方法可用于测量水的运动（扩散）和方向性（各向异性），作为评估白色物质完整性的指标。为了确定早期损伤后WM改变的范围和程度，我们将对20名单侧PL儿童（11-18岁）和40名性别和年龄匹配的对照儿童的大脑进行成像。从DWI数据集，我们将获得的扩散和各向异性的措施，在以前确定的WM衰减的地区，并在主要的大脑通路。此外，标准MRI方法将用于测量纵向弛豫时间（T1）和质子密度（MO），以开始区分可能导致异常各向异性的WM紊乱类型。

DESCRIPTION (provided by applicant): A common goal of research on various developmental brain disorders is to understand how an insult to the system affects the subsequent development of the brain. Toward this objective, we have studied cognitive and brain development in children with unilateral pre- or perinatal brain lesions (PL) for over a decade. Our longitudinal, behavioral studies have shown that children with PL have milder deficits than adult patients, and in the domain of language, the mapping between lesion site and ensuing deficits differs from adults. The mildness of children's impairments and the mismatch in functional mapping suggests an alteration in the structure and organization in the neural substrate. To examine the macroanatomic structure of the intact brain, we previously used noninvasive magnetic resonance imaging (MRI) techniques. The MRI analysis of neuroanatomical brain development revealed reduced cerebral white matter (WM) volume in both the ipsilesional and contralesional hemispheres. The WM attenuation was region-specific and occurred in sites that would typically maintain projections to or through the site of injury. Heretofore the opportunity to examine WM tracts noninyasively has been limited by standard MRI techniques. In order to examine structural changes in intact WM fiber tracts following early disruption, this study will use diffusion weighted imaging (DWI) and quantitative analysis techniques. DWI is sensitive to the movement of water molecules. In the brain, cell membranes and myelin sheaths restrict the movement of water such that molecules moves more readily parallel to axon fibers than perpendicular to them. Thus DWI methods can be used to measure water movement (diffusion) and directionality (anisotropy) as indices to assess white matter integrity. To determine the extent and degree of WM alteration following early injury, we will image the brains of 20 children with unilateral PL (11-18 years old) and 40 sex- and age-matched control children. From the DWI datasets we will derive measures of diffusivity and anisotropy in regions of previously identified WM attenuation and in the major cerebral pathways. In addition, standard MRI methods will be used to measure longitudinal relaxation time (T1) and proton density (MO) to begin to differentiate types of WM disorder that may underlie abnormal anisotropy.