High-resolution three-dimensional-pQCT images can be an adequate basis for in-vivo μFE analysis of bone
High-resolution three-dimensional-pQCT images can be an adequate basis for in-vivo μFE analysis of bone
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DOI：
10.1115/1.1352734
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发表时间：
2001-04-01
影响因子：
1.7
通讯作者：
Rüegsegger, P
中科院分区：
文献类型：
--
作者：
Pistoia, W;van Rietbergen, B;Rüegsegger, P
基于高分辨率图像的微观有限元（mu FE）模型已经能够计算体外骨小梁的弹性特性。最近，已经开发了在体内对骨小梁结构进行成像的技术，尽管分辨率较低。目前的工作研究的有用性，这种在体内的图像的μ FE分析，通过比较他们的μ FE结果的模型的基础上，高分辨率微CT（μ CT）图像。从人股骨头获得的15个标本进行成像，第一次与3D-pQCT扫描仪在165妈妈的分辨率和第二次与μ CT扫描仪在56妈妈的分辨率。第三组图像的分辨率为165 μ m，通过缩小mu CT测量创建。直接从这些图像创建mu FE模型。正交各向异性弹性性能和平均组织von Mises应力的标本计算从六个FE=分析每个标本。将165妈妈模型的结果与56妈妈模型的结果进行了比较，该模型作为参考模型。从基于pQCT的模型计算的结果与从参考模型计算的模量（R-2 > 0.95）和平均组织von Mises应力（R-2 > 0.83）的结果具有极好的相关性。根据缩小的微型CT模型计算的结果与参考模型的结果甚至更好地相关（模量的R-2 > 0.99，平均von Mises应力的R-2 > 0.96）。然而，在基于3D-pQCT的模型的情况下，回归线的斜率小于1，必须进行校正。泊松比的预测对于分别基于3D-pQCT和缩小的μ CT图像的模型而言不太准确（R-2 > 0.45和R-2 > 0.67）。缩小的mu CT图像和原始mu CT图像的结果几乎相同，这一事实表明，在3D-pQCT测量的情况下需要校正不是由于图像的体素大小，而是由于这些图像中的较高噪声水平和较低对比度，以及在165微米图像上应用滤波程序。总的来说：基于3D-pQCT的体内图像的μ FE模型的结果可以非常类似于从基于更高分辨率μ CT系统的μ FE模型获得的结果。
Micro-finite element (mu FE) models based on high-resolution images have enabled the calculation of elastic properties of trabecular bone in vitro. Recently, techniques have been developed to image trabecular bone structure in vivo, albeit at a lesser resolution. The present work studies the usefulness of such in-vivo images for mu FE analyses, by comparing their mu FE results to those of models based on high-resolution micro-CT (mu CT) images. Fifteen specimens obtained from human femoral heads were imaged first with a 3D-pQCT scanner at 165 mum resolution and a second time with a mu CT scanner at 56 mum resolution. A third set of images with a resolution of 165 mum was created by downscaling the mu CT measurements. The mu FE models were created directly from these images. Orthotropic elastic properties and the average tissue von Mises stress of the specimens were calculated from six FE=analyses per specimen. The results of the 165 mum models were compared to those of the 56 mum model, which was taken as the reference model. The results calculated from the pQCT-based models, correlated excellent with those calculated from the reference model for both moduli (R-2 > 0.95) and for the average tissue von Mises stress (R-2 > 0.83). Results calculated from the downscaled micro-CT models correlated even better with those of the reference models (R-2 > 0.99 for the moduli and R-2 > 0.96 for the average von Mises stress). In the case of the 3D-pQCT based models, however, the slopes of the regression lines were less than one and had to be corrected. The prediction of the Poisson's ratios was less accurate (R-2 > 0.45 and R-2 > 0.67) for the models based on 3D-pQCT adn downscaled mu CT images respectively). The fact that the results from the downscaled and original mu CT images were nearly identical indicates that the need for a correction in the case of the 3D-pQCT measurements was not due to the voxel size of the images but due to a higher noise level and a lower contrast in these images, in combination with the application of a filtering procedure at 165 micron images. In summary: the results of mu FE models based on in-vivo images of the 3D-pQCT can closely resemble those obtained from mu FE models based on higher resolution mu CT system.