Arterial Spin Labeling for fMRI

描述(由申请人提供)：本项目的目标是开发和表征动脉自旋标记(ASL)作为功能磁共振成像(FMRI)的工具，并确定在什么条件下ASL是 功能磁共振成像优于血氧依赖对比(BOLD)。ASL是一种 无创性脑血流成像技术--无线电 频率脉冲通过磁反转来标记动脉血液。资金的流入 标记的血液由核磁共振观察，并提供密切相关的信号 去CBF。利用ASL对脑血流量进行定量一直是本课题研究的重点 实验室在过去的几年里。虽然这极大地改善了CBF 在量化方面，仍然存在显著的误差和差异来源 在不被理解的ASL技术之间。这项工作的一个具体目标 是进一步改进使用ASL的CBF量化，重点放在三个方面 潜在重要但相对未开发的区域：与层流相关 TAG推注的分散；全球和局部CBF变化之间的差异； 以及ASL信号的心脏调制。定量ASL的应用 包括直接医疗应用，例如诊断、治疗评估 中风的风险评估，fMRJ对比机制的研究，以及 定量功能磁共振成像，所有这些都将受益于这一技术的发展 明确目标。一个新的研究领域是探索非量化的使用 ASL用于功能磁共振脑成像。在定量ASL中，有相当数量的 为了达到对几个主要问题的不敏感，人们牺牲了敏感性 系统误差的来源。相对于粗体，ASL的主要缺点是 对于脑图来说，它的敏感度明显降低，而主要的 ASL的优点是ASL信号到大脑的空间局部化 组织(大概是大脑活动的部位)被认为更好。 与BOLD fMRI相比，这项工作的第二个具体目标是开发新的ASL 最大限度地提高对大脑激活的敏感性的技术，而不需要考虑 CBF定量，第三个具体目标是检验以下假设 功能性ASL信号更好地定位于灰质而不是粗体。

DESCRIPTION (Provided by Applicant): The goals of this project are to develop and characterize arterial spin labeling (ASL) as a tool for functional magnetic resonance imaging (fMRI), and to determine under what conditions ASL is preferable to blood oxygenation dependent contrast (BOLD) for fMRI. ASL is a noninvasive technique for imaging of cerebral blood flow (CBF) that uses radio frequency pulses to tag arterial blood by magnetic inversion. The inflow of tagged blood is observed by MRI, and provides a signal that is closely related to CBF. The quantitation of CBF using ASL has been a focus of research in this laboratory over the past several years. While this has greatly improved CBF quantitation, there remain significant sources of error and discrepancies between ASL techniques that are not understood. One specific aim of this work is to further improve the quantitation of CBF using ASL, focusing on three potentially significant but relatively unexplored areas: laminar flow related dispersion of the tag bolus; differences between global and local CBF changes; and cardiac modulation of the ASL signal. Applications of quantitative ASL include direct medical applications such as diagnosis, evaluation of treatment, and risk assessment for stroke, the study of fMRJ contrast mechanisms, and quantitative fMRI, all of which will benefit from the developments of this specific aim. A new area of research is to explore the use of non-quantitative ASL for fMRI brain mapping. In quantitative ASL, a significant amount of sensitivity is sacrificed in order to achieve insensitivity to several major sources of systematic errors. The major disadvantage of ASL relative to BOLD for brain mapping is that it is significantly less sensitive, while the main advantage of ASL is that the spatial localization of the ASL signal to brain tissue (and presumably to the site of brain activity) is thought to be better than for BOLD fMRI The second specific aim of this work is to develop new ASL techniques that maximize the sensitivity to brain activation without regard for CBF quantitation, and the third specific aim is to test the hypothesis that the functional ASL signal is better localized to gray matter than BOLD.