Subject- and site-specific modeling techniques greatly improve finite element models (FEMs) derived from clinical-resolution CT data. A variety of density-modulus relationships are used in scapula FEMs, but the sensitivity to selection of relationships has yet to be experimentally evaluated. The objectives of this study were to compare quantitative-CT (QCT) derived FEMs mapped with different density-modulus relationships and material mapping strategies to experimentally loaded cadaveric scapular specimens. Six specimens were loaded within a micro-CT (33.5 μm isotropic voxels) using a custom-hexapod loading device. Digital volume correlation (DVC) was used to estimate full-field displacements by registering images in pre- and post-loaded states. Experimental loads were measured using a 6-DOF load cell. QCT-FEMs replicated the experimental setup using DVC-driven boundary conditions (BCs) and were mapped with one of fifteen density-modulus relationships using elemental or nodal material mapping strategies. Models were compared based on predicted QCT-FEM nodal reaction forces compared to experimental load cell measurements and linear regression of the full-field nodal displacements compared to the DVC full-field displacements. Comparing full-field displacements, linear regression showed slopes ranging from 0.86 to 1.06, r-squared values of 0.82-1.00, and max errors of 0.039 mm for all three Cartesian directions. Nearly identical linear regression results occurred for both elemental and nodal material mapping strategies. Comparing QCT-FEM to experimental reaction forces, errors ranged from - 46 to 965% for all specimens, with specimen-specific errors as low as 3%. This study utilized volumetric imaging combined with mechanical loading to derive full-field experimental measurements to evaluate various density-modulus relationships required for QCT-FEMs applied to whole-bone scapular loading. The results suggest that elemental and nodal material mapping strategies are both able to simultaneously replicate experimental full-field displacements and reactions forces dependent on the density-modulus relationship used.

中文翻译：

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QCT衍生肩cap骨模型的材料映射：与使用数字体积相关性的Micro-CT加载标本的比较。

特定于主题和站点的建模技术极大地改善了从临床分辨率CT数据得出的有限元模型（FEM）。肩cap骨有限元模型中使用了多种密度-模量关系，但对关系选择的敏感性尚待实验评估。这项研究的目的是比较定量CT（QCT）导出的具有不同密度模量关系的FEM和材料映射策略与实验加载的尸体肩cap骨标本。使用定制六脚架加载设备将六个样本加载到微型CT（33.5μm各向同性体素）中。数字体积相关性（DVC）用于通过在加载前和加载后状态下注册图像来估算全场位移。使用6-DOF称重传感器测量实验负载。QCT-FEM使用DVC驱动的边界条件（BC）复制了实验装置，并使用元素或节点材料映射策略以15个密度-模量关系之一进行了映射。基于预测的QCT-FEM节点反作用力与实验测力传感器的测量结果进行了比较，并对模型的全场节点位移与DVC的全场位移进行了线性回归。比较全视场位移，线性回归显示所有三个笛卡尔方向的斜率范围为0.86至1.06，r平方值为0.82-1.00，最大误差为0.039 mm。对于元素和节点材料映射策略，几乎都发生了线性回归结果。将QCT-FEM与实验反作用力进行比较，所有样本的误差范围为-46至965％，标本特定误差低至3％。这项研究利用体积成像结合机械负荷来获得全场实验测量结果，以评估应用于全骨肩骨负荷的QCT-FEM所需的各种密度-模量关系。结果表明，元素和节点材料映射策略都能够同时复制实验性的全场位移和反作用力，具体取决于所使用的密度模量关系。