Department of Radiology, Stanford University, Stanford, CA 94395, USA.
Department of Physics and Astronomy "Augusto Righi", University of Bologna, 40127 Bologna, Italy.
Int J Mol Sci. 2021 Jul 7;22(14):7318. doi: 10.3390/ijms22147318.
Nuclear Magnetic Resonance (NMR) is a well-suited methodology to study bone composition and structural properties. This is because the NMR parameters, such as the T2 relaxation time, are sensitive to the chemical and physical environment of the H nuclei. Although magnetic resonance imaging (MRI) allows bone structure assessment in vivo, its cost limits the suitability of conventional MRI for routine bone screening. With difficulty accessing clinically suitable exams, the diagnosis of bone diseases, such as osteoporosis, and the associated fracture risk estimation is based on the assessment of bone mineral density (BMD), obtained by the dual-energy X-ray absorptiometry (DXA). However, integrating the information about the structure of the bone with the bone mineral density has been shown to improve fracture risk estimation related to osteoporosis. Portable NMR, based on low-field single-sided NMR devices, is a promising and appealing approach to assess NMR properties of biological tissues with the aim of medical applications. Since these scanners detect the signal from a sensitive volume external to the magnet, they can be used to perform NMR measurement without the need to fit a sample inside a bore of a magnet, allowing, in principle, in vivo application. Techniques based on NMR single-sided devices have the potential to provide a high impact on the clinical routine because of low purchasing and running costs and low maintenance of such scanners. In this review, the development of new methodologies to investigate structural properties of trabecular bone exploiting single-sided NMR devices is reviewed, and current limitations and future perspectives are discussed.
磁共振（NMR）是研究骨成分和结构特性的一种非常合适的方法。这是因为 NMR 参数，如 T2 弛豫时间，对 H 核的化学和物理环境敏感。尽管磁共振成像（MRI）允许在体内评估骨结构，但由于其成本限制了常规 MRI 对常规骨筛查的适用性。由于难以进行临床适用的检查，骨疾病（如骨质疏松症）的诊断和相关骨折风险评估是基于骨矿物质密度（BMD）的评估，通过双能 X 射线吸收法（DXA）获得。然而，将骨结构信息与骨矿物质密度相结合，已被证明可以提高与骨质疏松症相关的骨折风险评估。基于低场单边 NMR 设备的便携式 NMR 是一种很有前途和吸引力的方法，可用于评估生物组织的 NMR 特性，以实现医学应用。由于这些扫描仪从磁体外部的敏感体积中检测信号，因此可以在无需将样品装入磁体孔的情况下进行 NMR 测量，从而原则上允许进行体内应用。基于 NMR 单边设备的技术具有为临床常规带来重大影响的潜力，因为这些扫描仪的购买和运行成本低，且维护成本低。在这篇综述中，回顾了利用单边 NMR 设备研究小梁骨结构特性的新方法的发展，并讨论了当前的局限性和未来的前景。
