Enhancing Bone Quality Assessment Using Quantitative Ultrasound

描述（由申请人提供）：与骨质疏松症相关的骨折风险代表了一个问题，随着国家人口老龄化，这一问题可能变得更加严重。FDA已经批准了7种旨在减缓或逆转骨质疏松症的药物。监测药物治疗的金标准是双能X射线吸收测定法（DEXA），它提供了骨矿物质密度（BMD）的测量。原则上，骨超声测量能够提供有关骨质量的额外信息，因为它不仅对骨矿物质密度敏感，而且对影响骨折风险的微观结构和方向敏感。然而，尽管超声测量法很有前途，但尚未显示出能提供这种额外的骨质信息，部分原因是在拟议的研究中要解决的具体限制。在接收换能器处的相位抵消对骨超声具有负面影响。超声通过骨的传输导致产生多种传播模式，包括快波和慢波、模式转换和多重散射-这些效应可以掩盖决定骨折风险的骨的基本材料特性。目前，超声测量仅限于允许通过传输的部位，如跟骨，而骨折风险最高的部位，如髋关节，只能使用反向散射超声。因此，我们确定了三个具体目标：1）识别、分离和克服由接收换能器处的相位消除引起的基于当前传输的跟骨声谱测量的限制，2）实现超声信号的贝叶斯反演，以根据接收到的传输声谱测量信号来估计潜在的骨材料性质，所述传输声谱测量信号由于多个模式的存在而复杂化，以及3）验证、扩展，并改进基于后向散射超声估计高危部位（如髋关节）骨折风险的方法。拟议研究的长期目标是增强和扩展骨超声测量，以促进其在监测骨质和骨质疏松症的潜在回归中的作用，并借助药物干预。公共卫生相关性：骨质疏松性骨折降低生活质量，并带来巨大的医疗费用。超声测量法可以改善骨质量评估，因为与DEXA不同，它对骨的微观结构和方向敏感。拟议的研究解决了对现有超声技术的根本改进，并探索了适用于骨折风险相对较高但目前无法监测的髋关节和脊柱的新技术。

DESCRIPTION (provided by applicant): Fracture risk associated with osteoporosis represents a concern that is likely to become ever more serious as the nation's population ages. The FDA has approved 7 drugs designed to slow or reverse osteoporosis. The gold standard for monitoring pharmacological treatment is Dual Energy X-ray Absorptiometry (DEXA), which provides a measure of bone mineral density (BMD). In principle, bone sonometry is capable of providing additional information regarding bone quality because it is sensitive not only to bone mineral density but also to microstructure and orientation which influence fracture risk. In spite of its promise, however, sonometry has not yet been shown to provide such additional bone quality information, in part because of the specific limitations to be addressed in the proposed research. Phase cancellation at the receiving transducer has a negative impact on bone sonography. Transmission of ultrasound through bone is results in the generation of multiple modes of propagation including fast and slow waves, mode convertion, and multiple scattering - effects that can mask the underlying material properties of bone that determine fracture risk. At present, sonometry is limited to sites permitting through transmission such as the cancaneus, whereas sites at highest risk of fracture such as the hip would be accessible only to backscattered ultrasound. We have therefore identified three specific aims: 1) Identify, segregate, and overcome limitations of current transmission-based calcaneus sonometry arising from phase cancellation at the receiving transducer, 2) implement Bayes inversion of the ultrasonic signals to estimate the underlying bone material properties from received transmission sonometry signals complicated by the presence of multiple modes, and 3) validate, expand, and refine methods for estimating fracture risk in high risk sites such as the hip based on backscattered ultrasound. The long-term goal of the proposed research is to enhance and expand bone sonometry to facilitate its role in monitoring bone quality and the potential regression of osteoporosis with the aid of pharmacological interventions. PUBLIC HEALTH RELEVANCE: Osteoporotic fractures reduce quality of life and carry enormous health care costs. Sonometry could improve bone quality assessment because, unlike DEXA, it is sensitive to bone microstructure and orientation. The proposed research addresses fundamental improvements to existing sonometry techniques, and explores new techniques applicable to the hip and spine that are at relatively high risk of fracture but currently cannot be monitored.