White Matter Diffusion MRI in Children With Early Stroke

描述（由申请人提供）：研究各种大脑发育障碍的共同目标是了解对系统的侮辱如何影响大脑的后续发育。为了实现这一目标，我们研究了十多年来患有单侧产前或围产期脑损伤（PL）的儿童的认知和大脑发育。我们的纵向行为研究表明，与成人患者相比，患有PL的儿童有轻微的缺陷，并且在语言领域，病变部位和随后的缺陷之间的映射与成人不同。儿童损伤的轻度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，我们以前使用无创磁共振成像（MRI）技术。神经解剖脑发育的MRI分析显示，同侧和对侧半球的脑白质（WM）体积均减少。WM衰减是区域特异性的，发生在通常会向损伤部位或通过损伤部位保持突起的部位。迄今为止，标准的MRI技术限制了对WM束进行无创检查的机会。为了检查早期破坏后完整WM纤维束的结构变化，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，使得分子更容易与轴突纤维平行而不是垂直运动。因此，DWI方法可以用来测量水的运动（扩散）和方向性（各向异性）作为评估白质完整性的指标。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数据集中，我们将得出先前确定的WM衰减区域和主要脑通路的扩散率和各向异性的测量。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.