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。灌流是营养物质通过动脉输送到毛细血管床的过程。脑灌流是大脑生理过程中不可或缺的动态部分，无论是在心理过程中，还是在静息状态和自然衰老过程中。在神经科学和诊断成像领域，开发成像体内生理学的工具具有巨大的价值。磁共振成像(MRI)具有多功能性和非侵入性，是发展新的成像技术的一种极好的手段。磁共振灌注成像技术可以用来研究生理、功能和结构之间的相互作用，包括脑血管、灰质和白质。最令人兴奋的MRI进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Gd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，并在感兴趣的组织区域下游被检测到，例如在灰质中。ASL还可以用来显示动脉或静脉中“标记”的血液水的运动。随着ASL物理学的发展，它可以用来描述健康成年人生命周期内的自然血流模式，因此它是这项赠款提案的重点。预期的结果如下：1)更好地了解血液流动模式在衰老过程中如何变化并导致大脑灰质的灌注量减少，2)证明ASL与DSC相比的价值，以及3)ASL技术的发展，以改进对白质的评估。

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.