Noninvasive tools for assessing muscle structure and function

项目摘要 肌肉力量和僵硬的变化是控制姿势和运动的基础。这些基本能力 几乎所有的运动障碍都会受损，包括中风、脑瘫、 肌肉骨骼损伤或疼痛。康复可以用重新建立健康的模式来框定 每个病人的肌肉力量和僵硬。因此，生物力学领域的一个根本挑战， 运动控制和身体康复长期以来一直在测量健康和健康人的肌肉力量和僵硬 疾病，然而，没有严格的方法来做到这一点的非侵入性。超声横波弹性成像 (SWE)被认为是一种无创性的测量硬度的工具，但我们已经证明了SWE是 不仅对肌肉僵硬敏感，而且对力也敏感，这些依赖关系因肌肉类型而异。 虽然我们的结果质疑了之前许多研究的结论，但它们也表明SWE可能 被重新想象为一种非侵入性测量刚度和力的工具。这项建议的目的是 评估这一耐人寻味的可能性，它可能会改变人类运动的研究，并指导康复 治疗多种运动障碍的方案。 我们的长期目标是改进与肌肉变化相关的肌肉骨骼疾病的治疗。 力或刚度。我们的中心假设是肌肉僵硬和力量可以唯一地由 考虑到肌肉的独特结构，Swe。横波传播对以下变化很敏感 肌肉应力(按横截面面积归一化的力)和硬度，但SWE是否可以 独立测量这些量。目标1和目标2将量化被动延长和 主动收缩改变了平行于肌肉纤维方向的横波传播，由 目前可用于临床的一维超声阵列。研究将在动物模型中进行 因此，SWE测量可以与肌肉硬度和应力的直接测量(目标1)进行比较，在此之前 考虑到被认为具有内部应力变化的几块人类肌肉的复杂性(目标2)。 最后，我们将评估我们开发的使用多方向SWE来确定 肌肉应力和僵硬无创(目标3)；这将使用3D打印生物材料的组合来实现 已知的机械性能，从我们的动物模型中收获的肌肉，以及人类实验 严格测试这一创新方法，并根据需要对其进行调整，以适应肌肉的独特结构。 我们希望我们的目标将准确地阐明当前SWE应用程序正在衡量的是什么 并确定一种使用多方向SWE的新方法是否可以用于测量肌肉力量 和非侵入性僵硬。这种能力将对康复具有变革性，提供量化的 对肌肉的关键特性的评估，这些特性使人类能够运动或导致运动受损。

Project Summary Changes in muscle force and stiffness underlie the control of posture and movement. These fundamental abilities are impaired in almost all movement disorders, including those resulting from stroke, cerebral palsy, musculoskeletal injury, or pain. Rehabilitation can be framed in terms of re-establishing healthy patterns of muscle force and stiffness for each patient. Consequently, a fundamental challenge in the fields of biomechanics, motor control, and physical rehabilitation has long been measuring muscle force and stiffness in health and disease, yet there are no rigorous methods for doing so noninvasively. Ultrasound shear wave elastography (SWE) was proposed as a noninvasive tool for measuring stiffness, but we have demonstrated that SWE is sensitive not only to muscle stiffness but also to force, and that these dependencies vary across muscle types. While our results call into question conclusions from many previous studies, they also suggest that SWE could be reimagined as a tool for noninvasively measuring both stiffness and force. The objective of this proposal is to evaluate this intriguing possibility, which could transform the study of human movement and guide rehabilitation protocols for numerous motor disorders. Our long-term goal is to improve treatments for musculoskeletal disorders associated with changes to muscle force or stiffness. Our central hypothesis is that muscle stiffness and force can be uniquely determined from SWE by considering the distinctive structure of muscle. Shear wave propagation is sensitive to changes in muscle stress (force normalized by cross-sectional area) and stiffness, but it remains unknown if SWE can independently measure these quantities. Aims 1 and 2 will quantify how stresses from passive lengthening and active contraction alter shear wave propagation parallel to the direction of muscle fibers, as measured by the one-dimensional ultrasound arrays currently available in clinics. Studies will be conducted in an animal model so that SWE measurements can be compared to direct measures of muscle stiffness and stress (Aim 1), before considering the complexities of several human muscles thought to have internal variations in stress (Aim 2). Finally, we will evaluate the novel technique we have developed that uses multi-directional SWE to determine muscle stress and stiffness noninvasively (Aim 3); this will occur using a combination of 3D-printed biomaterials with known mechanical properties, muscles harvested from our animal model, and human experiments to rigorously test this innovative approach and adapt it as needed to account for the unique structure of muscle. We expect that our aims will clarify precisely what is being measured by current applications of SWE to muscle and determine if a novel approach employing multidirectional SWE can be used to measure muscle force and stiffness noninvasively. Such an ability would be transformative for rehabilitation, providing quantitative assessments of the critical properties of muscle that enable human movement or contribute to its impairment.