Probing long bones using ultrasound with machine learning: signal processing, simulation, inversion, and pattern recognition

骨质疏松症是最常见的骨骼疾病之一，其特征在于骨量减少、微结构退化和皮质骨变薄，导致骨脆性和骨折风险。这种疾病可以发生在任何年龄的任何性别，但绝经后的妇女更容易患上这种疾病。骨丢失发生时没有任何症状，直到骨头变得脆弱而断裂。 骨质疏松症每年在全世界造成890多万例骨折，仍然是最流行的未确诊疾病之一。 大多数患者，谁的经验，骨质疏松性骨折，失去了他们的生活质量，特别是自由行动的意愿。因此，预防、能够准确诊断和监测骨质疏松症和脆性骨折至关重要。 目前，骨完整性主要通过使用双能X射线吸收测定法（DXA）测量骨矿物质密度（BMD）来评估。 然而，临床研究表明，在正常和骨质疏松骨中测量的BMD值显示出相当大的重叠;因此，BMD不能为骨质疏松症的准确诊断提供足够的信息，因为基于X射线的测量未能考虑骨结构和机械特性。 在所有的方法中，定量导波超声（QGWU）已被证明是有前途的潜力，在离体和体内评估骨完整性。与金标准DXA相比，QGWU的一个优势是它能够提供与骨强度相关的机械性能测量。皮层夹在软组织和骨髓之间，起到超声波导的作用。被捕获在皮质内的超声反射并增强成高能超声导波（UGW）能量的“束”，以沿着沿着长骨行进。 UGW对材料厚度和弹性特性敏感，因此具有探测长骨皮质的几何和材料特性的潜力。 该提案提供了一个机会，可以开发创新和智能的基于超声的成像技术，以区分健康和骨质疏松人群，并诊断和监测骨骼疾病的进展，这将改善患者的护理。这里的工作为培养高素质人才提供了良好的环境。有一个强烈的强调交叉施肥的几个学科（医学物理学，生物医学工程，生物物理学，计算机科学），以解决医疗相关的问题。这项研究计划的结果将导致新的和智能的方法和技术开发的超声表征骨骼的能力和完整性。软件开发和换能器阵列的设计，以更好地测量与骨强度相关的皮质变薄和骨刚度，将导致可能的机会，专利和技术商业化使用超声导波。

Osteoporosis is one of the most common skeletal disorders characterized by reduced bone mass, micro-structural deterioration, and cortical bone thinning, leading to bone fragility and fracture risks. The disease can occur in either gender at any age, but women after menopause are more susceptible to the disease. The bone loss occurs silently without any symptoms until the bone is weak to break. Osteoporosis causes more than 8.9 million fractures annually worldwide and remains one of the most prevalent undiagnosed disease. Most patients, who experience osteoporotic fractures, lose their quality of life and especially the will to move freely. Therefore, preventing, being able to diagnose accurately, and monitoring osteoporosis and fragility fractures are of supreme importance. Currently, bone integrity is mainly assessed by measuring bone mineral density (BMD) using dual-energy X-ray absorptiometry (DXA). However, clinical studies indicated that BMD values measured in normal and osteoporotic bones showed considerable overlap; therefore, BMD does not provide sufficient information for accurate diagnosis of osteoporosis because X-ray based measurements fail to consider bone structural and mechanical properties. Among all methods, quantitative guided wave ultrasound (QGWU) has demonstrated its promising potential in the ex-vivo and in-vivo assessment of bone integrity. An advantage of QGWU over the gold-standard DXA is its ability to provide measurements of mechanical properties, relevant to bone strength. The cortex, which is sandwiched between soft tissue and marrow, acts as an ultrasound waveguide. The ultrasound trapped within the cortex reverberates and reinforces into a “bundle” of energetic ultrasonic guided waves (UGW) energy to travel along the long bone. UGW are sensitive to material thickness and elastic properties and thus, have the potential to probe the geometric and material properties of the cortex of long bones. The proposal offers an opportunity to develop innovative and smart ultrasound-based imaging technologies to discriminate healthy and osteoporotic populations and to diagnose and monitor the progression of bone diseases, which will improve patient care. The work here provides an excellent environment to train highly qualified personnel. There is a strong emphasis on cross-fertilization of several disciplines (medical physics, biomedical engineering, geophysics, computer science) to solve a medical-relevant problem. The findings of this research plan will lead to new and smart methodologies and technology development for ultrasound characterization of skeleton competence and integrity. Software development and design of transducer array to better measure cortical thinning and bone stiffness relevant to bone strength will lead to possible opportunities for patent and technology commercialization using ultrasonic guided waves.