MRI Mapping of Venous Oxygenation

描述（由申请人提供）：本工作的总体目标是开发一种基于MRI的无创方法，用于绘制氧提取分数（OEF）。OEF被认为是卒中半影区（灌注不足但可挽救的脑组织）比其他量更具体的指标，因此对于卒中患者管理中的谨慎决策非常重要。OEF也是了解BOLD功能成像中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物，因为已知这两个量之间存在紧密关系。最近的工作表明，全脑测量OEF可以使用T2测量头部的主要引流静脉。我们将开发一种新的方法，将映射T2，从而OEF整个大脑，提供区域特定的信息。我们的方法由三个模块组成：1）使用新的速度选择性激励方案选择性激励移动自旋; 2）使用流入动脉血的反转标记使动脉信号归零;以及3）使用流动补偿多回波或T2准备成像的T2标测。我们已经对每个组件提出了技术改进建议，并将实施、测试和优化这些改进。我们将量化OEF测量中残留误差的来源，以便很好地表征该方法的准确性。在这项工作的结论，我们希望有一个优化的方法，在人脑中的非侵入性OEF测量，提供了一个坚实的基础，为进一步的技术开发和/或转化研究。

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.