The New York Center for Biomedical Engineering, New York, NY 10024, USA.
J Bone Miner Res. 2012 Dec;27(12):2562-72. doi: 10.1002/jbmr.1710.
The local variability of microarchitecture of human trabecular calcaneus bone is investigated using high-resolution micro-computed tomography (µCT) scanning. The fabric tensor is employed as the measure of the microarchitecture of the pore structure of a porous medium. It is hypothesized that a fabric tensor-dependent poroelastic ultrasound approach will more effectively predict the data variance than will porosity alone. The specific aims of the present study are as follows: (1) to quantify the morphology and local anisotropy of the calcaneus microarchitecture with respect to anatomical directions; (2) to determine the interdependence, or lack thereof, of microarchitecture parameters, fabric, and volumetric bone mineral density (vBMD); and (3) to determine the relative ability of vBMD and fabric measurements in evaluating the variance in ultrasound wave velocity measurements along orthogonal directions in the human calcaneus. Our results show that the microarchitecture in the analyzed regions of human calcanei is anisotropic, with a preferred alignment along the posterior-anterior direction. Strong correlation was found between most scalar architectural parameters and vBMD. However, no statistical correlation was found between vBMD and the fabric components, the measures of the pore microstructure orientation. Therefore, among the parameters usually considered for cancellous bone (ie, classic histomorphometric parameters such as porosity, trabecular thickness, number and separation), only fabric components explain the data variance that cannot be explained by vBMD, a global mass measurement, which lacks the sensitivity and selectivity to distinguish osteoporotic from healthy subjects because it is insensitive to directional changes in bone architecture. This study demonstrates that a multidirectional, fabric-dependent poroelastic ultrasound approach has the capability of characterizing anisotropic bone properties (bone quality) beyond bone mass, and could help to better understand anisotropic changes in bone architecture using ultrasound.
采用高分辨率微计算机断层扫描（µCT）对人跟骨小梁的微观结构的局部变异性进行研究。织物张量作为多孔介质孔隙结构微观结构的度量。假设基于织物张量的多孔弹性超声方法将比单独使用孔隙率更有效地预测数据方差。本研究的具体目的如下：（1）定量分析跟骨微观结构的形态和局部各向异性与解剖方向的关系；（2）确定微观结构参数、织物和体积骨矿物质密度（vBMD）之间的相互依赖性或缺乏相互依赖性；（3）确定 vBMD 和织物测量在评估人跟骨正交方向上超声波速度测量方差方面的相对能力。我们的结果表明，分析的人类跟骨区域的微观结构具有各向异性，沿后前方向具有优先取向。大多数标量结构参数与 vBMD 之间存在很强的相关性。然而，在 vBMD 和织物分量（即，孔隙微观结构取向的度量）之间未发现统计学相关性，这是骨质量的度量，缺乏对骨质疏松和健康受试者进行区分的敏感性和选择性，因为它对骨结构的方向性变化不敏感。这项研究表明，多向、依赖于织物的多孔弹性超声方法具有描述各向异性骨骼特性（骨质量）的能力，超出了骨量，并且可以帮助更好地理解超声的骨骼结构各向异性变化。
