SKELETAL MUSCLE BY MR ELASTOGRAPHY

许多研究必须更好地了解肌肉的形态和生理学，以及损伤和相关疾病的病因。主动力生成器、被动力传递与结缔组织之间的相互作用是复杂的，需要进一步研究。近年来发展起来的磁共振弹性成像(MRE)技术为无创活体研究提供了巨大的潜力。磁共振成像成像组织对声波剪切波的反应，以确定肌肉中的剪切模数和张力。本研究的具体目的是：目的1：开发在不同载荷条件下对骨骼肌声横波进行成像的实用方法：开发专门为将横波应用于骨骼肌而设计的机电驱动器和支撑装置。开发一种具有3轴运动编码的多层螺旋MRE脉冲序列，适用于大视场下骨骼肌的横波成像。开发具有类似能力的3D采集序列。评估缩短获取时间的各种方法。设计并制作了一种MRI兼容的肌肉负荷系统。目的2：建立骨骼肌MR弹性成像的图像分析方法：开发和测试几种不同的测量MRE图像中局部波长的方法。在算法中加入调整，以适应在初步研究中观察到的波导现象。开发使用MRI获得的肌肉体积信息来估计局部纤维张力的方法。目的：利用磁共振弹性成像技术研究活体正常肌肉：将磁共振弹性成像技术应用于活体研究，以提供志愿者四肢肌肉的弹性成像图像。肌肉的基本特性，包括肌肉的模数或硬度作为张力、负荷率和扰动频率的函数将被验证。还将检查肌肉内张力分布的一致性。目的4：利用磁共振弹性成像技术研究活体异常肌肉：将磁共振弹性成像技术应用于活体，提供异常肌肉的弹性成像图像，以区分正常肌肉和病变肌肉的生理。这项技术的成功应用将为评估各种康复程序的效果提供一种手段。

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.