Probing ultrasonic waves through long bones with soft tissues and inversion

骨质疏松症是最常见的骨骼疾病之一，其特征是骨量减少、微结构恶化、皮质骨变薄和松质骨穿孔，导致骨脆性和骨折风险。腕部、髋部和脊柱骨质疏松性骨折的流行是一个严重的公共卫生问题，影响着全世界约2亿人，特别是在老龄化人口中。目前，骨质量的评估主要是通过双能x线骨密度（BMD）来评估。然而，临床研究表明，在正常和骨质疏松的骨骼中测量的BMD值有相当大的重叠；因此，骨密度测量不能为准确诊断提供足够的信息。骨质疏松症仍然是当今世界上最普遍的未确诊疾病之一。这是由于基于辐射的方法没有考虑骨弹性和小梁微结构。近年来，定量超声（QUS）作为一种很有前途的骨质量评估技术受到了广泛的关注。超声波没有电离辐射。定量超声（QUS）利用机械波探测骨内部结构，因此对骨组织弹性和与骨强度相关的建筑结构敏感。体外和体内研究都表明，超声波能够穿透骨骼，并以体波和导波的形式在长骨皮层内传播。*这一建议提供了一个机会，进一步加强我们对在轴向传输采集配置中控制超声与软组织/皮层系统相互作用的物理原理的基本理解。在这方面的知识是至关重要的，为QUS在临床上成功应用定量骨状态提供信心和理由。采用超声相控阵系统可以提高采集效率，缩短采集时间。创新的多通道信号处理技术将用于提高信噪比，并分离体波和导波能量以进行进一步分析。骨参数如弹性常数将被倒置，并与人体骨密度相关。本研究计划的发现将导致新的和更好的方法和技术的发展，超声表征骨骼的能力和完整性。

Osteoporosis is one of the most common skeletal disorders characterized by reduced bone mass, micro-structural deterioration, cortical bone thinning, and cancellous bone perforation leading to bone fragility and fracture risks. The prevalence of osteoporotic fractures of the wrists, hips, and spines is a serious public health problem affecting about 200 million people worldwide especially in the aging population. Currently, bone quality is assessed mainly by bone mineral density (BMD) using dual energy x-ray absorptiometry (DEXA). However, clinical studies indicated that BMD values measured in normal and osteoporotic bones showed considerable overlap; therefore, BMD measurements do not provide sufficient information for accurate diagnosis. Osteoporosis still remains one of the most prevalent undiagnosed diseases in the world today. This is due to the failure to consider bone elasticity and trabecular microstructures by radiation-based methods. Recently, quantitative ultrasound (QUS) has gained considerable attention as a promising technology to assess bone quality. Ultrasound is free of ionizing radiation. Quantitative ultrasound (QUS) uses mechanical waves to probe the internal bone structure and is, therefore, sensitive to bone tissue elasticity and architectural structure relevant to bone strength. Both in-vitro and in-vivo studies have shown that ultrasound is capable to penetrate bone and travel within the cortex of long bones in the form of bulk and guided waves. *This proposal offers an opportunity to further enhance our fundamental understanding of the physical principles governing the ultrasound interaction with soft tissue/cortex system in an axial transmission acquisition configuration. The knowledge in this area is crucial to provide confidence and justification for successful application of QUS to quantify bone status clinically. Ultrasound phased array system will be used to enhance acquisition efficiency and decrease acquisition time. Innovative multichannel signal processing techniques will be used to enhance signal-to-noise ratio and separate bulk and guided wave energies for further analysis. Bone parameters such as elastic constants will be inverted and correlated with BMD using human subjects. The findings of this research plan will lead to new and better methodologies and technology development for ultrasound characterization of skeleton competence and integrity.