Advances in Magnetic Resonance Imaging (MRI) of Flow

血流磁共振成像 (MRI) 的进展

• 批准号: 249886-2012
• 负责人: Newling, Benedict
• 金额: $ 1.82万
• 依托单位: University of New Brunswick
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=547438
• 关键词: Advances; Magnetic; Resonance; Imaging; MRI

Steady fluid flow at low speeds is laminar: layers of fluid slide smoothly past one another in an ordered way. When the flow becomes fast enough or when it happens in a sufficiently large vessel, the flow is turbulent: there is complicated and unpredictable mixing of the fluid. Turbulent fluid flow has fascinated scientists since the time of Leonardo da Vinci, but despite nearly 600 years of study, we are still occasionally surprised by the features of turbulence. This is a frustration for scientists and engineers, because an understanding of turbulent flow is important in the atmosphere, in rivers, through dams and turbines, around fish and submarines, in chemical plants, through rocks and inside the human body. In a quest to improve our understanding, we make measurements of fluid flow. This proposal concerns the development of improved measurements for the study of fluid flows in general, but turbulent fluid flows in particular. We will use magnetic resonance imaging (MRI) equipment, which is in principle identical to those used in hospital scans, to measure turbulent flow. MRI is a fabulous tool for the measurement of flow, because it can look inside opaque fluids like foams or slurries and because it does not disturb the flow at all - no probe or tracer need be inserted. Our particular MRI flow measurement method is unique for two reasons. The measurement time is very short (for MRI), which allows us to measure a much broader range of flow speeds than other MRI methods. The measurement time is constant for all parts of our data acquisition, which eliminates certain artefacts to which other MRI methods are prone, particularly in flows like foams, which contain a mixture of liquid and gas. In this proposal we develop some of the hardware used in our method, we extend the method to measure the character of the turbulent flow in all directions, we refine the techniques that we use to select our region of interest within the flow and we study turbulence in some fluids that no other technique can cope with. All of these developments will afford us new insight into the deceptively complicated phenomenon of turbulence.

低速下的稳定流体流动是层流：流体层以有序的方式平滑地滑过彼此。当流动变得足够快或当它发生在足够大的容器中时，流动是湍流的：存在复杂且不可预测的流体混合。自列奥纳多达芬奇时代以来，湍流就一直吸引着科学家们，但尽管经过了近600年的研究，我们仍然偶尔会对湍流的特征感到惊讶。这对科学家和工程师来说是一个挫折，因为对湍流的理解在大气中，在河流中，通过水坝和涡轮机，在鱼和潜艇周围，在化工厂，通过岩石和人体内是很重要的。为了提高我们的理解，我们对流体流动进行测量。该建议涉及改进测量的发展，用于研究一般的流体流动，但特别是湍流流体流动。我们将使用磁共振成像（MRI）设备来测量湍流，该设备在原理上与医院扫描中使用的设备相同。MRI是一种极好的测量流量的工具，因为它可以查看泡沫或泥浆等不透明流体的内部，而且它根本不会干扰流量-无需插入探头或示踪剂。我们特殊的MRI流量测量方法是独一无二的，原因有二。测量时间非常短（对于MRI），这使我们能够测量比其他MRI方法更宽的流速范围。对于我们的数据采集的所有部分，测量时间都是恒定的，这消除了其他MRI方法容易出现的某些伪影，特别是在包含液体和气体混合物的泡沫等流动中。在这个建议中，我们开发了一些在我们的方法中使用的硬件，我们扩展的方法来测量在各个方向上的湍流的特性，我们完善的技术，我们用来选择我们的感兴趣的区域内的流动，我们研究湍流在一些流体中，没有其他技术可以科普。所有这些发展将使我们对看似复杂的湍流现象有新的认识。