Mitton D, Cendre E, Roux J P, Arlot M E, Peix G, Rumelhart C, Babot D, Meunier P J
Laboratoire de Mécanique des Solides, INSA, Lyon, France.
Bone. 1998 Jun;22(6):651-8. doi: 10.1016/s8756-3282(98)00036-2.
The goal of the present study was to determine if a high-resolution computed tomography (HRCT) system with 150 microns resolution was sufficient to predict mechanical properties in ewe lumbar vertebrae. To answer this question, we used a triangular comparison between: HRCT; biomechanics (compression and shear tests); and histomorphometry, which was the reference method for the measurements of morphometric parameters. Two dissected lumbar vertebrae (L-4 and L-5) from 32 ewes were used. Both compressive and shear properties correlated significantly with amount of bone and structural parameters evaluated by histomorphometry (bone volume/tissue volume, trabecular thickness, trabecular separation), but no significant correlation was found with the trabecular number. With our shear test involving the trabecular architecture itself more significant correlations were found with the node-strut analysis parameters than from the compressive test. Significant correlations were also found between HRCT and histological parameters (bone volume/tissue volume, bone surface/bone volume, trabecular separation, trabecular number, total strut length, number of nodes, and number of termini). Correlations between HRCT structural parameters and mechanical properties on L-4 were of the same magnitude as the correlations between the histomorphometric structural parameters and mechanical results on L-5 but with the remarkable advantage the HRCT is a noninvasive method. In spite of the resolution (150 microns) of our HRCT system, which entailed mainly an enlargement of the thinnest trabeculae or their loss during the segmentation process, we obtained coherent relationships between mechanical and tomographic parameters. The thinnest trabeculae probably had little effect on the mechanical strength. Also, this type of resolution allows us to consider the possibility of perfecting an in vivo HRCT system. However, physical density and bone mineral density correlated much better with strength than either classical histomorphometric or tomographic parameters. The current conclusion is fairly negative with respect to the ability of HRCT to assess mechanical properties nondestructively as compared with dual-energy X-ray absorptiometry. But, the noninvasive nature of the imaging modality and the capacity for three-dimensional imaging at arbitrary orientation make HRCT a promising tool in the quantitative assessment of cancellous architecture.
本研究的目的是确定分辨率为150微米的高分辨率计算机断层扫描（HRCT）系统是否足以预测母羊腰椎的力学性能。为了回答这个问题，我们采用了三角对比法，对比对象包括：HRCT；生物力学（压缩和剪切试验）；以及组织形态计量学，这是测量形态计量参数的参考方法。我们使用了32只母羊的两块解剖后的腰椎（L-4和L-5）。压缩和剪切性能均与通过组织形态计量学评估的骨量和结构参数（骨体积/组织体积、小梁厚度、小梁间距）显著相关，但与小梁数量无显著相关性。在我们涉及小梁结构本身的剪切试验中，与节点支柱分析参数的相关性比压缩试验中更显著。HRCT与组织学参数（骨体积/组织体积、骨表面/骨体积、小梁间距、小梁数量、总支柱长度、节点数量和末端数量）之间也存在显著相关性。HRCT结构参数与L-4力学性能之间的相关性与组织形态计量学结构参数与L-5力学结果之间的相关性大小相同，但HRCT具有显著优势，即它是一种非侵入性方法。尽管我们的HRCT系统分辨率为150微米，这主要导致最细的小梁在分割过程中变粗或丢失，但我们在力学和断层扫描参数之间获得了连贯的关系。最细的小梁可能对力学强度影响很小。此外，这种分辨率使我们能够考虑完善体内HRCT系统的可能性。然而，物理密度和骨矿物质密度与强度的相关性比经典组织形态计量学或断层扫描参数都要好得多。与双能X射线吸收法相比，目前关于HRCT无损评估力学性能能力的结论相当负面。但是，成像方式的非侵入性以及任意方向三维成像的能力使HRCT成为松质骨结构定量评估中有前景的工具。
