Quantitative and Spectroscopic Imaging of Skeletal Muscle Changes in Sarcopenia at High Field

项目摘要 骨质疏松症是一种以老年人肌肉质量和功能丧失为特征的疾病，其发病率正在上升 由于美国人口老龄化，这与美国的相关性很大。人们普遍认为，肌肉的虚弱 骨质疏松症不能仅用肌肉质量的减少来解释，但其背后的机制仍然很不清楚。 明白了。这在一定程度上是由于缺乏非侵入性技术来观察肌肉结构和 高细节的构图。我们建议开发MRI技术来测量肌肉形态， 显微结构和脂肪含量，以详细了解患者肌肉数量和质量的变化 骨质疏松症及其与更容易获得的肌肉功能测量(如握力)之间的关系 力量和步态速度。这将对正在进行的关于如何实现这一目标的辩论作出重要贡献 测量可以用来定义石棺减少症，这将为治疗开发铺平道路。 我们的目标是开发利用超高场研究肌肉结构和组成的新方法。 核磁共振检查。具体地说，我们的目标是(1)获得基于水的骨骼肌宏观和微观图像 无与伦比的效率、图像质量和分辨率；(2)获取图像的空间分布 骨骼肌中的肌内脂肪，测量甲基和亚甲基以估计饱和度；和(3) 通过观察T2的MR测量来比较骨骼肌的结构和质量 松弛率、扩散率(分别作为炎症和纤维大小的替代指标)、脂肪含量和脂质 石膏症受试者和健康对照组的肌肉成分，看看这些量与肌肉的相关性 功能。 这个项目有几个创新方面。首先，我们将开发一种估计肌肉形态T2的方法 松弛速率和扩散率的单一磁共振序列。重要的是，这将使开发的方法 易于在其他核磁共振站点运行。其次，我们将设计方法来执行稳健、高效的成像 高场下人骨骼肌细胞内脂滴分布及饱和度研究。两个都是 这些方法将具有无与伦比的信噪比和对图像伪影的鲁棒性。这个 这项工作的意义在于研究炎症、纤维大小和脂质分布在动脉粥样硬化中的作用 骨质疏松症中肌肉的减弱，以及这些测量与肌肉功能的关系。由此产生的 结论和技术可能有助于建立定义石棺减少的共同标准，并有助于 这种疾病的未来治疗方法的发展。

Project Summary Sarcopenia, a condition characterized by loss of muscle mass and function in the elderly, is of increasing relevance in the United States due to its aging population. It is generally agreed that the weakening of the muscle in sarcopenia cannot be explained by loss of muscle mass alone, but the mechanisms behind this remain poorly understood. This is partly due to the lack of non-invasive techniques for observing muscle structure and composition in high detail. We propose to develop MRI techniques to measure muscle morphology, microstructure, and fat content to get a detailed view of the changes in muscle quantity and quality in patients with sarcopenia and how they relate to more easily attainable measurements of muscle function such as grip strength and gait speed. This would provide an important contribution to the ongoing debate about how such measurements could be used to define sarcopenia, which would pave the way for treatment development. We aim to develop novel methods to investigate the structure and composition of muscle using ultra-high-field MRI. Specifically, we aim to (1) obtain water-based images of skeletal muscle macro- and microstructure with unparalleled efficiency, image quality, and resolution; (2) obtain images of the spatial distribution of intramyocellular lipids in skeletal muscle, measuring both methyl and methylene to estimate saturation; and (3) to conduct a study comparing skeletal muscle structure and quality by looking at MR measurements of T2 relaxation rates, diffusivity (as proxies for inflammation and fiber size, respectively), fat fraction, and lipid composition, in subjects with sarcopenia and healthy controls and see how these quantities correlate to muscle function. This project has several innovative aspects. First, we will develop a method to estimate muscle morphology, T2 relaxation rates, and diffusivity with a single MRI sequence. Importantly, this will make the developed method easy to run at other MRI sites. Second, we will devise methods to perform robust, efficient imaging of intramyocellular lipid droplet distribution and saturation in human skeletal muscle in vivo at high field. Both of these methods will have unparalleled signal-to-noise ratio and robustness against image artifacts. The significance of this work is the investigation of the role of inflammation, fiber size, and lipid distribution in the weakening of muscle in sarcopenia and how these measurements are related to muscle function. The resulting conclusions and techniques may help establish a common standard for the definition of sarcopenia and aid in the development of future treatments for this condition.