MRI Mapping of Venous Oxygenation

描述（由申请人提供）：这项工作的总体目标是开发一种基于无创MRI的氧提取分数（OEF）制图方法。OEF被认为是比其他数量更具体的半暗带（灌注不足但可挽救的脑组织）指标，因此对中风患者管理的审慎决策很重要。在BOLD功能成像中，OEF也是理解脑代谢和对比机制的关键因素。在这项工作中，静脉T2将被用作静脉氧合的替代品，因为已知这两个量之间存在紧密的关系。最近的研究表明，可以通过测量头部主要引流静脉的T2来测量全脑的OEF。我们将开发一种新的方法，绘制整个大脑的T2和OEF，提供区域特定信息。我们的方法由三个模块组成：1)使用一种新的速度选择激励方案对运动自旋进行选择性激励；2)利用动脉血流入的反转标记来消除动脉信号；3)利用流量补偿多回波或T2准备成像对T2进行测绘。我们提出了对这些组件的技术改进，并将实现、测试和优化这些改进。我们将量化OEF测量中残余误差的来源，以便该方法的准确性得到很好的表征。在这项工作的最后，我们期望有一种优化的方法来测量人脑的非侵入性OEF，为进一步的技术开发和/或转化研究提供坚实的基础。

DESCRIPTION (provided by applicant): The overall objective of this work is to develop a non-invasive MRI based method for mapping of Oxygen Extraction Fraction (OEF). OEF is thought to be a more specific indicator of penumbra (under perfused but salvageable brain tissue) in stroke than other quantities, and is therefore important for prudent decision-making in the management of stroke patients. OEF is also a key factor in the understanding of cerebral metabolism and contrast mechanisms in BOLD functional imaging. In this work, venous T2 will be used as a surrogate for venous oxygenation, as there is known to be a tight relationship between these two quantities. Recent work has shown that whole-brain measurements of OEF can be made using T2 measurements in the major draining veins of the head. We will develop a new approach that will map T2 and thereby OEF throughout the brain, providing regionally specific information. Our approach is comprised of three modules: 1) selective excitation of moving spins using a novel velocity selective excitation scheme; 2) nulling of arterial signal using inversion tagging of inflowing arterial blood; and 3) mapping of T2 using flow compensated multi-echo, or T2 prepared imaging. We have proposed technical improvements to each of these components, and will implement, test, and optimize these improvements. We will quantify the sources of residual errors in the OEF measurement so that the accuracy of the method is well characterized. At the conclusion of this work, we expect to have an optimized method for non-invasive OEF measurement in the human brain that provides a solid foundation for further technical development and/or translational research. PUBLIC HEALTH RELEVANCE: This project will produce a new non-invasive MRI based method for mapping of the oxygen extraction fraction (OEF) of the brain. OEF is thought to be the best marker for the detection of salvageable brain tissue in stroke patients, and imaging of this measure may significantly improve decision making in the treatment of these patients. In addition, non-invasive OEF mapping will allow for a better understanding of energy metabolism in the brain, as well as the physiological basis of functional brain imaging using blood oxygenation level dependent (BOLD) contrast.