Measurements of mobile and bound water by nuclear magnetic resonance correlate with mechanical properties of bone
Measurements of mobile and bound water by nuclear magnetic resonance correlate with mechanical properties of bone
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DOI：
10.1016/j.bone.2007.09.049
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发表时间：
2008-01-01
期刊：
影响因子：
4.1
通讯作者：
Wang, Xiaodu
中科院分区：
文献类型：
--
作者：
Nyman, Jeffry S.;Ni, Qingwen;Wang, Xiaodu
由于骨矿物质密度的临床测量不一定能预测一个人是否会在没有干预的情况下骨折，因此需要找到评估骨质量的补充工具。目前，我们假设通过核磁共振（NMR）技术测量的流动水和结合水分别与骨强度和韧性相关。为了测试这一点，我们从 18 名男性捐赠者身上采集了 18 根人类股骨中段骨干的弯曲标本，并将其分为中年组和老年组。对每个水合样品进行 NMR 测量后，使用反演技术将自由感应衰变数据转换为自旋-自旋 (T2) 弛豫率的分布。然后，分布分解为三种不同的成分，可能代表固体氢、与骨组织结合的水以及占据骨样本内微观孔隙的流动水。结合组分和移动组分的积分信号强度通过样品的湿质量标准化。 NMR 测量后，进行三点弯曲测试以确定每个样本的弹性模量、弯曲强度和断裂功。接下来，测量孔隙率、矿物质与胶原蛋白的比率和戊糖素浓度。在这个人类皮质骨样本中，流动水量不存在与年龄相关的差异，但结合水量随着年龄的增加而减少，具有统计学意义。此外，结合水与骨的强度和骨折功相关，而流动水与弹性模量相关，并且似乎可以量化骨内微观孔隙的水平。另一方面，结合水与非酶胶原交联的浓度相关。这项研究的结果表明，利用磁共振技术量化流动水和结合水可以作为骨质量的指标。 (C) 2007 Elsevier Inc. 保留所有权利。
Since clinical measures of bone mineral density do not necessarily predict whether a person will fracture a bone without an intervention, there is a need to find supplementary tools for assessing bone quality. Presently, we hypothesized that measures of mobile and bound water by a Nuclear Magnetic Resonance (NMR) technique are correlated with bone strength and toughness, respectively. To test this, bending specimens from the mid-diaphysis of 18 human femurs were collected from 18 male donors and divided into middle aged and elderly groups. After NMR measurements of each hydrated specimen, an inversion technique was used to convert the free induction decay data into a distribution of spin-spin (T2) relaxation rates. Then, the distribution resolved into three distinct components that likely represent solid hydrogen, water bound to bone tissue, and mobile water that occupy microscopic pores within the bone specimen. The integrated signal intensities of the bound and mobile components were normalized by the wet mass of the specimen. Following NMR measurements, three point bending tests were conducted to determine the modulus of elasticity, flexure strength, and work to fracture of each specimen. Next, the porosity, mineral-to-collagen ratio, and pentosidine concentration were measured. In this sample of human cortical bone, there was no age-related difference in the amount of mobile water, but the decrease in the amount of bound water with increasing age was statistically significant. Moreover, bound water was associated with both strength and work to fracture of bone, while mobile water was correlated with modulus of elasticity and appeared to quantify the level of microscopic pores within bone. On the other hand, bound water was correlated with the concentration of non-enzymatic collagen cross-links. The results of this study indicate that quantifying mobile and bound water with magnetic resonance techniques could potentially serve as indicators of bone quality. (C) 2007 Elsevier Inc. All rights reserved.