科研之友
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摘要
Micro magnetic resonance imaging (mu MRI) is an in vivo imaging method that permits 3D quantification of cortical and trabecular bone microstructure. mu MR images can also be used for building microstructural finite element (mu FE) models to assess bone stiffness, which highly correlates with bone's resistance to fractures. In order for mu MRI-based microstructural and mu FE analyses to become standard clinical tools for assessing bone quality, validation with a current gold standard, namely, high-resolution micro computed tomography (mu CT), is required. Microstructural measurements of 25 human cadaveric distal tibias were performed for the registered mu MR and mu CT images, respectively. Next, whole bone stiffness, trabecular bone stiffness, and elastic moduli of cubic subvolumes of trabecular bone in both mu MR and mu CT images were determined by voxel-based mu FE analysis. The bone volume fraction (BV/TV), trabecular number (Tb.N*), trabecular spacing (Tb.Sp*), cortical thickness (Ct.Th), and structure model index (SMI) based on mu MRI showed strong correlations with mu CT measurements (r(2) = 0.67 to 0.97), and bone surface-to-volume ratio (BS/BV), connectivity density (Conn.D), and degree of anisotropy (DA) had significant but moderate correlations (r(2) = 0.33 to 0.51). Each of these measurements also contributed to one or many of the mu FE-predicted mechanical properties. However, model-independent trabecular thickness (Tb.Th*) based on mu MRI had no correlation with the mu CT measurement and did not contribute to any mechanical measurement. Furthermore, the whole bone and trabecular bone stiffness based on mu MRI were highly correlated with those of mu CT images (r(2) = 0.86 and 0.96), suggesting that mu MRI-based mu FE analyses can directly and accurately quantify whole bone mechanical competence. In contrast, the elastic moduli of the mu MRI trabecular bone subvolume had significant but only moderate correlations with their gold standards (r(2) = 0.40 to 0.58). We conclude that most microstructural and mechanical properties of the distal tibia can be derived efficiently from mu MR images and can provide additional information regarding bone quality.
- 出版日期2010-9
