SKELETAL MUSCLE BY MR ELASTOGRAPHY

许多研究必须更好地了解肌肉的形态学和生理学以及损伤和相关疾病的病因。 主动力发生器、被动力传递和结缔组织之间的相互作用是复杂的，需要进一步研究。 磁共振弹性成像（MRE）是近年来发展起来的一项新技术，它为无创性的活体研究提供了巨大的潜力. MRE成像组织对声剪切波的响应，以确定剪切模量以及肌肉中的张力。 本研究的具体目的是：目的1：开发实用的方法，用于成像声剪切波在不同的负载条件下的骨骼肌：开发机电驱动器和支持设备，专门设计用于应用剪切波骨骼肌。开发具有3轴运动编码的MRE脉冲序列的多层版本，适用于在大视场内对骨骼肌中的剪切波进行成像。 开发具有类似功能的3D采集序列。 评估减少采集时间的各种方法。 设计和制造MRI兼容的肌肉加载系统。 目标二：开发骨骼肌MR弹性成像的图像分析方法：开发和测试几种不同的方法来测量MRE图像中的局部波长。 在算法中纳入调整，以适应在初步研究中观察到的波导现象。 发展使用MRI导出的肌肉体积信息来估计局部纤维张力的方法。 目标3：利用磁共振弹性成像研究体内正常肌肉：将在体内应用MRE技术，以提供志愿者四肢肌肉的弹性成像图像。 肌肉的基本特性，包括肌肉的模量或刚度作为张力的函数，加载速率和扰动频率将得到验证。 还将检查肌肉内张力分布的均匀性。 目标4：利用磁共振弹性成像研究体内异常肌肉：将在体内应用MRE技术，以提供异常肌肉的弹性成像图像，已知疾病，以区分正常和患病肌肉的生理学。这项技术的成功应用将为评估各种康复程序的疗效提供一种手段。

Numerous studies have to better understand the morphology and physiology of muscle and the etiology of injury and associated disorders. Interactions between the active force generator, passive force transmission, and the connective tissue are complicated and need to be further investigated. A newly developed technology, the Magnetic Resonance Elastography (MRE), provides great potential for in vivo investigation non- invasively. MRE images the response of tissue to acoustic shear waves to determine the shear modulus as well as the tension in the muscle. The specific aims of this study are: Aim 1: To Develop Practical Methods for Imaging Acoustic Shear Waves in Skeletal Muscle under Varied Loading Conditions: Develop electromechanical drivers and support devices that are designed specifically for applying shear waves to skeletal muscle. Develop a multislice version of the MRE pulse sequence with 3 axes of motion encoding, suitable for imaging shear waves in skeletal muscle over large fields of view. Develop a 3D acquisition sequence with similar capabilities. Evaluate various approaches for reducing acquisition time. Design and fabricate an MRI-compatable muscle loading system. Aim 2: To Develop Image Analysis Methods for MR Elastography of Skeletal Muscle: Develop and test several different approaches for measuring local wavelength in MRE images. Incorporate adjustments in the algorithms to accommodate waveguide phenomena that have been observed in preliminary studies. Develop methods for using MRI- derived muscle volumetric information to estimate regional fiber tension. Aim 3: To Utilize Magnetic Resonance Elastography to Study Normal Muscle In Vivo: The MRE technique will be applied in vivo to provide elastographic images of the muscles in the extremity of volunteers. Basic characteristics of muscle that include the moduli or stiffness of muscles as a function of the tension, the loading rate and the frequency of perturbation will be validated. Uniformity of tension distribution within the muscle will also be examined. Aim 4: To Utilize Magnetic Resonance Elastography to Study Abnormal Muscle In Vivo: The MRE technique will be applied in vivo to provide elastographic images of abnormal muscle, with known disorders to differentiate the physiology of normal and diseased muscle. Successful application of this technique will provide a means for assessing efficacy of various rehabilitation procedures.