Noninvasive Measurement Of Strain And Mechanical Properties In Tendons/Ligaments

描述(申请人提供)：我们提出了一种新的超声波分析范式，以便非侵入性地计算韧带和肌腱的力学性能(非线性刚度)和功能应变。力学性能可以诊断损伤或病理状态(例如肌腱炎或肌腱病)，并可以量化愈合的程度。组织应变表明康复和康复所需的功能负荷。如果成功，我们的方法将大大改进现有的方法，并发现许多有益于公众健康的应用。而且，它将为许多与NIAMS相关的肌肉骨骼研究提供一个改进的科学研究工具。本研究首次将声弹性(AE)技术应用于生物医学超声成像。声发射是一种数学理论，它严格描述了超声波在变形弹性材料中的传播，将反射波与机械性能和应变联系在一起。在肌腱或韧带等组织被拉伸(即功能加载)后，声发射比现有方法更准确地模拟波在变形介质中的传播。目前，其他基于超声的方法使用“波动理论”，该理论不能解释波速和波幅随变形的变化。初步研究清楚地表明，当使用超声波计算组织特性时，“波动理论”分析可能会导致重大误差。声发射分析有可能：1)避免这些误差，2)包括组织的非线性，3)通过一次功能加载获得所有必需的数据，以及4)几乎实时地计算应变和力学性能。这项技术不需要额外的力测量或耗时的数值建模来提取属性。据我们所知，没有一种现有的方法可以几乎实时地同时评估所施加的应变和非线性组织属性。这项研究将测试一种名为“声弹性应变计”(ASG)的基于声发射的技术在动物肌腱(大鼠和猪断肢后的肌腱)上的效果。肌腱将在原位进行分析，即通过皮肤和表层组织进行分析，同时使用力学测试系统进行拉伸。在这项研究中，ASG将应用于猪屈肌腱(完整的和诱导的亚失效损伤，以模拟不同程度的二度扭伤)。ASG将应用于大鼠跟腱(完整的和在手术断裂和不同时期愈合后)。在这两个动物模型中，将评估应用应变和原位拉伸肌腱的应变依赖的组织特性。ASG的应变将与机械测试系统的应变相关联，以证明ASG技术的准确性和可重复性。这项研究将确定ASG量化亚失效破坏程度的能力和灵敏度(通过极限力的降低来确定)。最后，这项研究将确定ASG在愈合过程中预测力量恢复的能力。与公共健康相关：我们提出了一种新的、不同的超声波分析方法，以非侵入性地测量软组织的机械性能和功能应变。如果成功，这种新的诊断工具将是对现有方法的重大改进，并将发现许多有益于公共卫生的应用。例如，考虑功能应变测量。在美国，2003年有超过1200万人因为膝盖或肩膀的问题去看整形外科医生。膝关节韧带损伤很常见，几乎所有的肩部问题都与功能负荷改变的组织拉伸或断裂有关。例如，考虑机械特性识别。美国癌症协会2005年估计，美国约有211,240名女性被诊断为浸润性乳腺癌，232,090名男性被诊断为前列腺癌。显然，用非侵入性组织应变来测量功能载荷和非侵入性力学特性来区分和识别组织类型将是有价值的。我们的方法有可能改进这些领域的现有方法。最近在联邦医疗保险人群中进行的一项研究预测，2020年肌肉骨骼成像的成本将为36亿美元，其中20亿美元将用于核磁共振。研究人员估计，45%的MRI诊断可以通过超声波进行，如果适当地替代，可以在未来14年节省近70亿美元的成本。超声波技术的创新发展可能会创造增值功能，从而增加人们的兴趣和重大意义。

DESCRIPTION (provided by applicant): We propose a new paradigm for ultrasound wave analysis in order to non-invasively compute mechanical properties (nonlinear stiffness) and functional strains in ligaments and tendons. Mechanical properties can diagnose damage or a pathologic state (i.e. tendonitis or tendinosis) and it can quantify the extent of healing. Tissue strains indicate functional loadings for rehabilitation and recovery. If successful, our method will significantly improve upon existing methods and find numerous applications that benefit public health. And, it will provide an improved tool for scientific inquiry in many musculoskeletal studies of relevance to NIAMS. This study applies acoustoelasticity (AE) to biomedical ultrasound imaging for the first time. AE is a mathematical theory that rigorously describes ultrasonic wave propagation in deformed elastic materials, interrelating reflected waves to mechanical properties and strain. After a tissue such as tendon or ligament is stretched (i.e. functionally loaded), AE models wave propagation in a deformed medium more accurately than existing methods. Currently, other ultrasound-based methods use "wave theory", which does not account for deformation-dependent changes in wave velocity and amplitude. Preliminary studies clearly show that "wave theory" analysis can cause significant errors when ultrasound is used to compute tissue properties. AE analysis has the potential to: 1) avoid these errors, 2) include tissue non-linearities, 3) acquire all requisite data with one functional loading, and 4) compute strain and mechanical properties in virtually real time. This technique does not require additional force measurements or time-consuming numerical modeling to extract properties. To our knowledge, no existing method can evaluate both applied strain and nonlinear tissue properties simultaneously in virtually real time. This study will test the efficacy of an AE-based technique termed "Acoustoelastic Strain Gauge" (ASG) on animal tendons (tendons in rat and pig limbs after sacrifice). Tendons will be analyzed in situ, that is, through skin and superficial tissues while being stretched with a mechanical test system. In this study ASG will be applied to porcine flexor tendons (intact and with induced subfailure damage to simulate various levels of 2nd degree sprains). ASG will be applied to rat Achilles tendons (intact and after surgical rupture and various periods of healing). In both animal models, applied strain and strain-dependent tissue properties of the in situ stretched tendons will be evaluated. Strain from ASG will be correlated with strain from a mechanical test system to demonstrate accuracy and repeatability of the ASG technique. This study will determine the ability and sensitivity of ASG to quantify the level of sub-failure damage (as determined by a reduction in ultimate force). Finally, this study will determine the ability of ASG to predict strength recovery during healing. PUBLIC HEALTH RELEVANCE: We propose a new and different method of ultrasound wave analysis to non-invasively measure mechanical properties and functional strains in soft tissues. If successful, this new diagnostic tool be a significant improvement over existing methods and will find numerous applications that benefit public health. Consider, for example, functional strain measurement. In the U.S. more than 12 million people visited orthopedic surgeons in 2003 because of either knee or shoulder problems. Knee ligament injuries are common, and almost all shoulder problems are related to stretched or ruptured tissues with altered functional loads. Consider, for example, mechanical property identification. The American Cancer Society estimated in 2005 that approximately 211,240 women were diagnosed with invasive breast cancer in the U.S. and 232,090 men were diagnosed with prostate cancer. Clearly, non-invasive tissue strain to measure functional loads and non-invasive mechanical properties to distinguish and identify tissue types would be valuable. Our method has the potential to improve upon existing methods in these areas. A recent study in a Medicare population projected that musculoskeletal imaging costs in 2020 will be $3.6 billion, of which $2 billion will be for MRI. Investigators estimated 45% of the MRI diagnoses could have been made with ultrasound, and if appropriately substituted, could result in cost savings of nearly $7 billion over the next 14 years. Innovative developments in ultrasound technology may create value added features resulting in increased interest and significant.