Expanding magnitude-based MRI relaxometry of human brain by using the complex signal for high resolution concomitant multiparametric and cerebrovascular mapping

磁共振成像（MRI）已成为一个不可或缺的工具，研究大脑结构，由于显着的对比，可以在MR图像中获得。近年来，许多图像处理工具已经变得容易获得，从而大大增加了研究大脑如何响应疾病和/或治疗的研究数量。尽管有过多的结果，但观察到的大脑变化与疾病/治疗的准确性和解释仍然受到这样一个事实的挑战，即这种方法依赖于定性MR图像，具有某种程度上任意的相对信号对比度。虽然定量MRI（qMRI）旨在捕获控制MRI信号的固有参数并揭示有关底层组织的微观结构信息，但qMRI参数标测的使用并不容易获得。最近出现的磁共振指纹（MRF）突出的认识，在MR社区，大脑的多参数地图是至关重要的发现所观察到的局灶性脑差异和其他组织微结构的变化的生物学基础。有趣的是，尽管大脑对氧气的需求很高，因此存在广泛的脑血管系统，但用于研究大脑结构的MR图像无法区分血管，因此在研究MR结构图像时未考虑其贡献。然而，当使用不同序列收集数据时，MRI可用于检测脑血管系统。**我在这里提出的研究计划试图整合扫描序列和采集的数据，使伴随的多参数和脑血管映射的人脑在临床相关的扫描时间在高分辨率。这将通过利用复杂（相位和幅度）MR信号并对数据采集方式进行小幅调整来实现。脉管系统的描绘将使得能够解开组织和血管的纠缠，从而产生更好地探测大脑的新颖且有效的方法，使得可以揭示在人脑的结构MR图像中观察到的体积变化/差异的生物源。此外，通过对水合状态和脑血流量的实验操作，我们将测量所产生的多参数图对微观结构变化的敏感性。这些实验还将能够测量水合作用和脑血流对大脑结构的形状和大小的影响，揭示和/或排除与结构MRI中使用的常见技术相关的可能混淆。总之，我们将能够推进我们对疾病/治疗中发生的微结构组织和血管变化的理解。

Magnetic Resonance Imaging (MRI) has become an indispensable tool to study brain structures due to the remarkable contrast that can be obtained in MR images. In recent years, numerous image processing tools have become readily available, thus drastically increasing the number of studies that look at how the brain changes in response to disease and/or treatment. Despite the plethora of results, the accuracy and interpretation of observed brain changes with disease/treatment remain challenged by the fact that such approaches rely on qualitative MR images with somewhat arbitrary, relative signal contrast. While quantitative MRI (qMRI) aims to capture inherent parameters that govern the MRI signal and reveal microstructural information about underlying tissue, the use of qMRI parametric mapping is not readily available. The recent advent of MR fingerprinting (MRF) highlights the recognition in the MR community that multiparametric maps of brain are critical for uncovering a biological basis for observed focal brain differences and other changes in tissue microstructure. Interestingly, despite the fact that the brain has a high demand for oxygen, and thus, there is extensive cerebral vasculature, the MR images that are used to study brain structures are not able to distinguish blood vessels and thus their contribution is not considered when studying MR structural images. However, MRI can be used to detect cerebral vasculature when different sequences are used to collect the data.******The research program I am proposing here attempts to consolidate scanning sequences and acquired data to enable concomitant multiparametric and cerebrovascular mapping of human brain at high resolution in a clinically relevant scan time. This will be achieved by exploiting the complex (phase and magnitude) MR signal and making small adjustment to the way the data is acquired. The depiction of vasculature will enable a disentanglement of tissue and blood vessels, resulting in a novel and efficient approach to better probe the brain such that a biological source of volumetric changes/differences observed in structural MR images of the human brain can be uncovered. Furthermore, through experimental manipulations of hydration status and cerebral blood flow, we will be measuring the sensitivity of the multiparametric maps produced, to changes in microstructure. These experiments will also enable measurements of the effects of hydration and cerebral blood flow on the shapes and sizes of brain structures, revealing and/or discarding possible confounds associated with common techniques used in structural MRI. In summary, we will enable the advancement of our understanding of the microstructural tissue and vascular changes that occur with disease/treatment.