Arterial Spin Labeling for fMRI

描述（由申请人提供）：本项目的目标是开发 并将动脉自旋标记（ASL）表征为功能性磁共振成像的工具。 共振成像（fMRI），并确定在什么条件下ASL是 对于功能磁共振成像，其优于血氧依赖对比度（BOLD）。ASL是一个 使用无线电的脑血流（CBF）成像的非侵入性技术 频率脉冲来标记动脉血液的磁反转。的流入 标记的血液通过MRI观察到，并提供了一个信号， 到CBF。利用ASL定量CBF一直是这一领域的研究热点 实验室在过去的几年里虽然这大大改善了CBF 尽管在定量方面存在着重大的误差和差异， 不了解的ASL技术之间的关系。这项工作的一个具体目标是 进一步改进使用ASL的CBF定量，重点是三个 潜在重要但相对未开发的领域：层流相关 标记团的分散;全局和局部CBF变化之间的差异; 和ASL信号的心脏调制。量化ASL的应用 包括直接医学应用，例如诊断、治疗评价 中风的风险评估，fMRJ对比机制的研究， 定量功能磁共振成像，所有这些都将受益于这一发展， 具体目标。一个新的研究领域是探索使用非定量的 功能磁共振成像脑成像的ASL。在定量ASL中， 为了实现对几种主要的不敏感性， 系统误差的来源。ASL相对于BOLD的主要缺点是 对于大脑映射来说，它的敏感性明显降低，而主要的 ASL的优点是ASL信号到大脑的空间定位 组织（可能是大脑活动的部位）被认为更好 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， CBF定量，第三个具体目的是检验假设， 功能性ASL信号比BOLD更好地定位于灰质。

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.