Precision of Digital Volume correlation approaches for strain analysis in Bone imaged with Micro-computed Tomography at Different Dimensional levels
Precision of Digital Volume correlation approaches for strain analysis in Bone imaged with Micro-computed Tomography at Different Dimensional levels
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DOI：
10.3389/fmats.2017.00031
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发表时间：
2017-11-08
影响因子：
3.2
通讯作者：
Tozzi, Gianluca
中科院分区：
文献类型：
--
作者：
Dall'Ara, Enrico;Pena-Fernandez, Marta;Tozzi, Gianluca
准确测量异质和各向异性骨组织中的局部应变对于理解肌肉骨骼疾病的病理生理学、评估临床前研究中的干预效果以及优化生物材料的设计和输送至关重要。数字体积相关（DVC）可以用来测量三维位移和应变场的加载试样的微计算机断层扫描（μ CT）图像。然而，这种方法受到输入图像的质量、所研究的组织的形态和密度、相关方案以及计算中使用的操作参数的影响。因此，对于每种应用，应评价方法的精密度。在本文中，我们提出了从以前的研究中分析的数据集收集的结果，以及最近的实验活动的新数据，用于表征两种不同的DVC方法的精度和输出的空间分辨率之间的关系。在零应变测试中处理用实验室源mu CT或同步加速器光mu CT（SR mu CT）扫描的不同骨结构，以评估DVC方法作为子体积大小（范围从8到2，500 μ m）的函数的精度。结果证实，对于每一个微观结构的DVC的精度提高较大的子体积尺寸，以下的幂律。然而，当使用SR mu CT或体内mu CT图像而不是传统的离体mu CT时，局部和全局DVC方法的精度的巨大差异首次得到了强调。这些研究结果表明，在SR μ CT设施中应用的原位机械测试协议应进行优化，以允许DVC分析的局部应变测量。此外，对于体内μ CT应用，DVC分析应仅以相对较低的空间分辨率进行，以实现该方法的合理精度。总之，我们已经广泛地表明，两种测试的DVC方法的精度受到不同的骨结构，不同的输入图像分辨率和不同的子体积大小的影响。在每次具体应用之前，DVC用户应始终采用类似的方法，以找到测量精度和空间分辨率之间的最佳折衷方案。
Accurate measurement of local strain in heterogeneous and anisotropic bone tissue is fundamental to understand the pathophysiology of musculoskeletal diseases, to evaluate the effect of interventions from preclinical studies, and to optimize the design and delivery of biomaterials. Digital volume correlation (DVC) can be used to measure the three-dimensional displacement and strain fields from micro-computed tomography (mu CT) images of loaded specimens. However, this approach is affected by the quality of the input images, by the morphology and density of the tissue under investigation, by the correlation scheme, and by the operational parameters used in the computation. Therefore, for each application, the precision of the method should be evaluated. In this paper, we present the results collected from datasets analyzed in previous studies as well as new data from a recent experimental campaign for characterizing the relationship between the precision of two different DVC approaches and the spatial resolution of the outputs. Different bone structures scanned with laboratory source mu CT or synchrotron light mu CT (SR mu CT) were processed in zero-strain tests to evaluate the precision of the DVC methods as a function of the subvolume size that ranged from 8 to 2,500 mu m. The results confirmed that for every microstructure the precision of DVC improves for larger subvolume size, following power laws. However, for the first time, large differences in the precision of both local and global DVC approaches have been highlighted when SR mu CT or in vivo mu CT images were used instead of conventional ex vivo mu CT. These findings suggest that in situ mechanical testing protocols applied in SR mu CT facilities should be optimized to allow DVC analyses of localized strain measurements. Moreover, for in vivo mu CT applications, DVC analyses should be performed only with relatively course spatial resolution for achieving a reasonable precision of the method. In conclusion, we have extensively shown that the precision of both tested DVC approaches is affected by different bone structures, different input image resolution, and different subvolume sizes. Before each specific application, DVC users should always apply a similar approach to find the best compromise between precision and spatial resolution of the measurements.