Perfusion and hemodynamics in brain imaging across the lifespan

大脑的燃料储备有限，必须依靠血液流动持续供应氧气和营养物质。灌注是营养物质通过动脉输送到毛细血管床的过程。灌注是大脑生理学中不可或缺的动态部分，在精神处理期间，在休息状态期间和在自然老化过程期间。在神经科学和诊断成像领域，开发体内生理成像工具具有巨大价值。磁共振成像（MRI）是多功能和非侵入性的，因此是开发新的成像技术的一种很好的方式。灌注MRI技术可用于研究生理、功能和结构之间的相互作用，包括脑血管、灰质和白色物质。最令人兴奋的MRI发展之一是动脉自旋标记（ASL），因为与正电子发射断层扫描（PET）或钆增强动态磁化率对比（DSC）MRI相比，它是完全无创的。动脉血液中的水分子被磁性“标记”，并在下游感兴趣的组织区域（如灰质）被检测到。ASL还可以被设计为对动脉或静脉中的“标记的”血液水的运动进行成像。随着ASL物理学的发展，它可以应用于在健康成年人的整个生命周期中观察自然灌注模式，因此它是这项拨款提案的重点。预期结果如下：1）对血流模式在衰老过程中如何变化以及导致大脑灰质灌注减少的理解得到改善，2）与DSC相比，ASL的价值得到证明，以及3）ASL技术的发展改善了对白色物质的评估。

The brain has limited fuel reserves and must rely on a continuous supply of oxygen and nutrients through blood flow. Perfusion is the process by which nutrients are delivered via arteries to the capillary bed. Perfusion is an integral, dynamic part of brain physiology, during mental processing, during the resting state and during the natural aging process. In the fields of neuroscience and diagnostic imaging, there is tremendous value in developing tools that image in-vivo physiology. Magnetic resonance imaging (MRI) is versatile and non-invasive, therefore an excellent modality to develop new imaging techniques. Perfusion MRI techniques can be used to study the interplay between physiology, function and structure, including cerebral vasculature, grey and white matter. One of the most exciting MRI developments is arterial spin labeling (ASL) because, compared to positron emission tomography (PET) or gadolinium enhanced dynamic susceptibility contrast (DSC) MRI, it is entirely non-invasive. Water molecules in the blood of arteries are "labeled" magnetically and detected downstream at tissue regions of interest, such as in the gray matter. ASL can also be designed to image movement of "tagged" blood water in arteries or veins. As the physics of ASL develops, it can be applied to characterise the natural perfusion patterns across the lifespan of healthy adult humans and it is thus the focus for this grant proposal. Anticipated results are the following: 1) an improved understanding of how blood flow patterns change during aging and cause a decrease in perfusion in the brain's gray matter, 2) a demonstration of the value of ASL when compared to DSC, and 3) development of ASL techniques to improve assessment of white matter.