Angular Dependency of T1 Relaxation Time in Cerebral White Matter in Ultrahigh Field MRI

项目总结 脑部磁共振成像(MRI)扫描的对比度受复杂因素的影响 水、脑大分子和微结构成分之间的相互作用。这个 最常用的基于MR弛豫的对比度随磁场强度变化， 因为T1和T2的MR弛豫时间都依赖于场。在更高的固有磁场中 组织特有的因素，如组织微结构导致的整体磁化率 和/或生化反应，影响松弛，从而影响MRI对比度。为提高效率 并在神经科学研究和临床诊断中充分利用磁共振图像，这是 了解组织相关因素对临床松弛对比的影响至关重要 (如3特斯拉=T)和超高场(UHF，7T或以上)MRI。 该方案的主旨是研究人类T1弛豫的角度依赖性 3T和7T时脑白质(WM)。我们的目标是了解MR-Visible的影响 水对WM中T1弛豫角的依赖关系。实验的目的是为了 研究磁场强度、轴突直径和磁化传递在脑损伤中的作用 MR可见水和T1弛豫时间的光纤对场的依赖关系。核磁共振数据将是 取自健康成年受试者，在3T和7T。该项目的具体目标如下 目标1：测量MR-可见光水的角度依赖关系的幅度和 并研究其与WM束轴突微结构的关系。 例如轴突直径。目的2：研究磁感应强度对磁场的依赖关系 MR-WM中可见的水和T1弛豫。目的：研究磁化作用的影响。 MR-可见光水角依赖的幅值转移和T1弛豫 3T和7T的WM时间。 该项目为我们增进对生物物理学的理解提供了长期的追求 磁共振成像的基础是脑部图像的对比。我们的首要目标是改进 正常脑及脑内病变的MRI组织形态勾画 现代神经成像技术。

PROJECT SUMMARY Contrast in magnetic resonance imaging (MRI) scans of the brain are influenced by complex interactions between water, brain macromolecules and microstructural compenents. The most commonly used MR relaxation-based contrasts change with magnetic field strength, because both T1 and T2 MR relaxation times are field dependent. At higher fields inherent tissue-specific factors, such as bulk magnetic susceptibility due to tissue microstructure and/or biochemical making, affect relaxation thereby influencing MRI contrast. For efficient and adequate use of MR images in neuroscientific research and clinical diagnosis, it is pivotal to understand effects of tissue-related factors on relaxation-based contrasts at clinical (such as 3 Tesla=T) and ultrahigh field (UHF, 7T or above) MRI. The thrust of the proposal is to study the angular dependency of T1 relaxation in human white matter (WM) at 3T and 7T. Our goal is to gain understanding of effects of MR-visible water on the angular dependency of T1 relaxation in WM. Experiments are designed to study the role of the magnetic field strength, axonal diameter and magnetization transfer in the fiber-to-field dependency of MR-visible water and T1 relaxation time. MRI data will be acquired from healthy adult participants at 3T and 7T. The specific aims of the project are as follows: AIM 1: to measure the amplitude of the angular dependency of MR-visible water and T1 relaxation time in WM and study its relationship with WM tracts axonal microstructure, such as axonal diameter. AIM 2: to study the magnetic field dependency of the amplitude of MR-visible water and T1 relaxation in WM. AIM3: to study the effects of magnetization transfer on the amplitude of the angular dependency of MR-visible water and T1 relaxation time in WM at 3T and 7T. The project adds to our long-term pursuit to advance understanding of biophysical underpinnings of MR contrasts in brain images. Our overarching goal is to improve delineation of tissue morphology by MRI for imaging of normal brain and its disorders in modern neuroimaging.