Bone & Joint Center, Henry Ford Hospital, Integrative Biosciences Center (iBio), 6135 Woodward, Detroit, MI 48202.
Department of Radiology, Henry Ford Hospital, One Ford Place, Suite 2F, Detroit, MI 48202.
J Biomech Eng. 2021 Oct 1;143(10). doi: 10.1115/1.4051280.
Vertebral fractures are the most common osteoporotic fractures, but clinical means for assessment of vertebral bone integrity are limited in accuracy, as they typically use surrogate measures that are indirectly related to mechanics. The objective of this study was to examine the extent to which intravertebral strain distributions and changes in cancellous bone texture generated by a load of physiological magnitude can be characterized using a clinically available imaging modality. We hypothesized that digital tomosynthesis-based digital volume correlation (DTS-DVC) and image texture-based metrics of cancellous bone microstructure can detect development of mechanical strains under load. Isolated cadaveric T11 vertebrae and L2-L4 vertebral segments were DTS imaged in a nonloaded state and under physiological load levels. Axial strain, maximum principal strain, maximum compressive and tensile principal strains, and von Mises equivalent strain were calculated using the DVC technique. The change in textural parameters (line fraction deviation, anisotropy, and fractal parameters) under load was calculated within the cancellous centrum. The effect of load on measured strains and texture variables was tested using mixed model analysis of variance, and relationships of strain and texture variables with donor age, bone density parameters, and bone size were examined using regression models. Magnitudes and heterogeneity of intravertebral strain measures correlated with applied loading and were significantly different from background noise. Image texture parameters were found to change with applied loading, but these changes were not observed in the second experiment testing L2-L4 segments. DTS-DVC-derived strains correlated with age more strongly than did bone mineral density (BMD) for T11.
椎体骨折是最常见的骨质疏松性骨折，但评估椎体骨完整性的临床手段准确性有限，因为它们通常使用与力学间接相关的替代指标。本研究的目的是检验在多大程度上可以使用临床可用的成像方式来描述生理负荷下的椎体内应变分布和松质骨纹理的变化。我们假设基于数字断层合成的数字体积相关（DTS-DVC）和松质骨微观结构的基于图像纹理的指标可以检测到负荷下机械应变的发展。将 T11 椎体和 L2-L4 椎体节段的离体尸体进行 DTS 成像，分别处于未加载状态和生理负荷水平下。使用 DVC 技术计算轴向应变、最大主应变、最大压缩和拉伸主应变以及 von Mises 等效应变。在松质骨中心内计算负荷下纹理参数（线分数偏差、各向异性和分形参数）的变化。使用混合模型方差分析测试加载对测量应变和纹理变量的影响，并使用回归模型检查应变和纹理变量与供体年龄、骨密度参数和骨大小的关系。椎体内应变测量的幅度和异质性与施加的载荷相关，与背景噪声明显不同。发现图像纹理参数随施加的载荷而变化，但在第二个测试 L2-L4 节段的实验中未观察到这些变化。与骨密度（BMD）相比，DTS-DVC 衍生的应变与 T11 年龄的相关性更强。
