Assessment of bone micro-structure using ultrasonic methods

骨质疏松症越来越普遍。它改变了微结构和骨密度，并评估了 两者中的一项是准确预测骨骼能力所必需的。几项研究已经证明了这一关系 骨微结构和骨强度之间的关系。然而，目前骨折风险的黄金标准 评估仅依赖于骨矿密度的X射线表征。一种定量、非侵入性和 骨微结构的非电离表征目前还不可能在体内实现。因此，有一种 未得到满足的需求。 我们建议通过开发一种新的技术来评估骨骼微结构来满足这一需求 使用超声多次散射的架构。我们假设当多重散射发生时 超声参数之间存在着可测量的关系，如散射平均自由 路径和微结构参数，如各向异性、连通性和小梁分离。 我们的方法基于以下两种模式： 第一：将骨微结构的特征与目前可用的评估相结合 骨密度有助于提高对骨折危险性的诊断。 第二：在兆赫范围内的超声波受到微结构的多次散射 在骨骼中繁殖过程中。产生的超声波信号是复杂的，并在微型计算机上嵌入信息。 建筑。 我们将有以下具体目标： SA.1利用数值模拟，我们将建立骨微结构与骨密度之间的定量关系 结构和超声参数。我们将创建类似骨骼的数字媒体，在其中我们将改变 微结构和材料特性独立，研究它们对超声的个体影响 传播。 SA.2使用3D打印，我们将创建具有任意和完全受控的微建筑的骨骼模型。 微结构和超声参数之间的关系将在 在幻影和真实标本中进行体外实验。 SA.3利用机械测试，我们将研究超声参数与微观结构参数之间的关系 建筑和机械方面的能力。 如果成功，这项研究将导致一种基于定量和非电离超声波的方法 以表征骨的微结构。最终，开发的方法将用于筛查， 骨质疏松的诊断和监测。这项研究旨在限制电离和昂贵的使用 骨质疏松症的诊断技术。

Osteoporosis is increasingly prevalent. It modifies microarchitecture and bone density and the assessment of both is required to predict bone competence accurately. Several studies have demonstrated the relationship between bone micro-architecture and bone strength. However, the current gold standard for fracture risk assessment relies on the X-ray characterization of bone mineral density alone. A quantitative, non-invasive and non-ionizing characterization of bone micro-architecture is currently not possible in vivo. There is therefore an unmet need. We propose to address this need by developing a novel technique for the assessment of bone micro- architecture using multiple scattering of ultrasound. We hypothesize that when multiple scattering occurs there is a measureable relationship between ultrasonic parameters, such as the scattering mean free path, and micro-architectural parameters, such as anisotropy, connectivity and trabecular separation. Our approach is based on the following two-fold paradigm: First: Combining the characterization of bone micro-architecture to the currently available assessment of bone mineral density would improve the diagnosis of fracture risk. Second: Ultrasound waves in the MHz range are subjected to multiple scattering by the micro-structure during propagation in bone. The resulting ultrasonic signals are complex and embed information on the micro- architecture. We will have the following specific aims: SA.1 Using numerical simulations, we will establish a quantitative relationship between bone micro- architecture and ultrasound parameters. We will create bone-like numerical media in which we will vary the micro-architectural and material properties independently, to study their individual influence on ultrasound propagation. SA.2 Using 3D printing, we will create bone phantoms with arbitrary and fully controlled micro-architecture. The relationship between the micro-architecture and ultrasound parameters will be experimentally studied in vitro in phantoms and real specimen. SA.3 Using mechanical testing, we will investigate the relationship between ultrasound parameters, micro- architecture and mechanical competence. If successful, this research will lead to a quantitative and non-ionizing ultrasound-based method to characterize bone micro-architecture. Ultimately, the methods developed will be used for screening, diagnosis and monitoring of osteoporosis. This research aims at limiting the use of ionizing and costly techniques for the diagnosis of osteoporosis.