Development of New Methods for Quantitative MRI

磁共振成像(MRI)在检查身体软组织方面非常有用，其能力仍在快速发展，使用量也在不断增加。磁共振成像的局限性之一是它往往不能提供准确的组织测量，而是通过比较不同区域的信号来进行相对测量。如果能为MRI开发出快速、准确的定量组织测量方法，它将进一步提高其提供精确信息的能力，这些信息将对医学成像和工业应用具有价值。我们的实验室专门通过利用每种图像对比度背后的MRI物理原理来生成新的MRI方法。我们的长期目标是不断开发新的方法，以增加MRI的价值，并以了解MRI物理及其与人体组织特性的关系为基础。这项研究计划将开发进行定量磁共振成像的新方法，重点是三种独特的定量技术。这三个感兴趣的领域是MRI应用的新兴领域，需要进一步发展才能成为实用工具。 第一个区域试图从最少量的扫描中确定多个定量MRI参数，称为MRI指纹识别。类似于侦探使用模式识别来确定物理指纹，我们使用MRI进化的模式识别来一次确定多个参数。我们将在这一领域开发利用标准MRI序列的独特贡献，这将使我们能够立即纳入标准MRI协议，而不需要冗长的额外扫描。这项工作建立在我们最近在单参数定量松弛映射方面的工作基础上。 第二个区域试图测量磁场，然后确定实际的磁化率分布。这一区域被称为定量易感图谱(QSM)。磁化率提供了一种独特的图像对比度形式，但QSM方法仍在发展中。我们将致力于提高QSM采集和处理方法的速度、稳定性和使用，以成像看不见的物体、血管、铁、钙和髓鞘。 第三个区域可以对大脑中的代谢物进行间接成像，称为化学交换饱和转移(CEST)。该方法提供了一种观察大脑化学性质的方法，包括神经递质含量和大脑酸度。我们将努力与同样使用磁共振成像的光谱技术相比较，进一步验证这些方法。这项工作对我们实验室来说是新的。 所有这三个领域的进展将包括新的后处理方法，新的成像序列，新的方法验证和人类定量MRI的新应用。这些进展将有助于将这些新兴的MRI方法转变为定量MRI的可行工具，并将为下一代成像科学家提供理想的培训环境。

Magnetic Resonance Imaging (MRI) is very useful for examining soft tissue in the body and is still rapidly evolving in capability and increasing in use. One of the limitations of MRI is it tends to not provide exact tissue measurements, instead making relative measurements by comparing the signal in different areas. If fast and exact quantitative tissue measures could be developed for MRI, it could further its ability to offer precise information which would be valuable for medical imaging and industrial uses. Our laboratory specializes in the generation of new MRI methods by exploiting the MRI physics underlying each form of image contrast. Our long term goal is the continual development of novel methods that increase the value of MRI and are based on understanding MRI physics and its relationship to human tissue properties. This research proposal will develop new means of performing quantitative MRI, focusing on three unique quantitative techniques. The three areas of interest are emerging areas of MRI application that require further evolution to become practical tools. The first area attempts to determine multiple quantitative MRI parameters from a minimal amount of scanning and is known as MRI fingerprinting. Similar to a detective's use of pattern recognition to determine a physical fingerprint, we use pattern recognition of MRI evolution to determine multiple parameters at once. We will develop unique contributions in this area that make use of standard MRI sequences, which would enable immediate incorporation into standard MRI protocols, without needing lengthy additional scans. This work builds on our recent work in single parameter quantitative relaxation mapping. The second area attempts to measure the magnetic field and then determine the actual magnetic susceptibility distribution. This area is known as Quantitative Susceptibility Mapping (QSM). The magnetic susceptibility provides a unique form of image contrast but the QSM methods are still evolving. We will work towards improving the speed, robustness and use of QSM acquisitions and processing methods to image invisible objects, blood vessels, iron, calcium and myelin. The third area enables indirect imaging of metabolites in the brain and is known as Chemical Exchange Saturation Transfer (CEST). The method provides a means to look at chemical properties of the brain including neurotransmitter content and brain acidity. We will work to further validate these methods in comparison to spectroscopic techniques that also use MRI. This work is new to our laboratory. The advances in all three areas will consist of new post-processing approaches, new imaging sequences, new validations of methods and new applications for human quantitative MRI. These advances will help turn these emerging MRI methods into viable tools for quantitative MRI and will provide ideal training environments for the next generation of imaging scientists.