Transversely isotropic elasticity imaging of cancellous bone.
Transversely isotropic elasticity imaging of cancellous bone.
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DOI：
10.1115/1.4004231
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发表时间：
2011-06
期刊：
影响因子：
--
通讯作者：
Morgan EF
中科院分区：
文献类型：
--
作者：
Shore SW;Barbone PE;Oberai AA;Morgan EF
为了测量生物材料力学性能的空间变化，先前的研究通常对切除的组织标本进行力学测试。然而，侵入性较小的测量在许多应用中更可取，例如患者特异性建模，疾病诊断以及跟踪与年龄或损伤相关的机械性能退化。弹性成像（elastography）是一种无损成像方法，通过测量应变场或位移场可以重建整个试样的弹性特性分布。迄今为止，弹性成像的大部分工作都涉及不可压缩的各向同性材料。本研究将弹性成像扩展到三维、可压缩、横向各向同性材料。描述了各向异性组织在组合准静载荷作用下的反问题的表述和求解方法，并提出了一种间接求得反问题解的优化正则化策略。然后考虑了横向各向同性弹性成像在人类椎骨松质骨中的几种应用。验证了利用各向同性弹性成像从实验中获得椎体松质骨材料特性分布重建的可行性。然而，仿真结果表明，各向异性材料不宜采用各向同性重构。进一步表明，横向各向同性方法确定了一种预测测量位移的解决方案，揭示了低刚度区域，并以约10%的误差恢复了所有五个弹性参数。发现给定弹性参数的恢复需要其相应应变的存在（例如，产生ε12的变形是重建C1212所必需的），并且正则化的应用表明可以提高精度。最后，论证了噪声对重建质量的影响，并确定了40 dB的信噪比（SNR）为从实验数据中获得准确重建的合理阈值。研究表明，在给定一组适当的位移场、正则化水平和信号强度的情况下，横向各向同性方法可以在不独立测量应力的情况下恢复所有五个弹性参数的相对量级。重建的质量随着对比度的增加、变形的大小和材料特性分布的不对称性而提高，这表明松质骨的弹性成像可以成为实验室研究中监测该组织损伤和疾病进展的有用工具。
To measure spatial variations in mechanical properties of biological materials, prior studies have typically performed mechanical tests on excised specimens of tissue. Less invasive measurements, however, are preferable in many applications, such as patient-specific modeling, disease diagnosis, and tracking of age- or damage-related degradation of mechanical properties. Elasticity imaging (elastography) is a nondestructive imaging method in which the distribution of elastic properties throughout a specimen can be reconstructed from measured strain or displacement fields. To date, most work in elasticity imaging has concerned incompressible, isotropic materials. This study presents an extension of elasticity imaging to three-dimensional, compressible, transversely isotropic materials. The formulation and solution of an inverse problem for an anisotropic tissue subjected to a combination of quasi-static loads is described, and an optimization and regularization strategy that indirectly obtains the solution to the inverse problem is presented. Several applications of transversely isotropic elasticity imaging to cancellous bone from the human vertebra are then considered. The feasibility of using isotropic elasticity imaging to obtain meaningful reconstructions of the distribution of material properties for vertebral cancellous bone from experiment is established. However, using simulation, it is shown that an isotropic reconstruction is not appropriate for anisotropic materials. It is further shown that the transversely isotropic method identifies a solution that predicts the measured displacements, reveals regions of low stiffness, and recovers all five elastic parameters with approximately 10% error. The recovery of a given elastic parameter is found to require the presence of its corresponding strain (e.g., a deformation that generates ε12 is necessary to reconstruct C1212), and the application of regularization is shown to improve accuracy. Finally, the effects of noise on reconstruction quality is demonstrated and a signal-to-noise ratio (SNR) of 40 dB is identified as a reasonable threshold for obtaining accurate reconstructions from experimental data. This study demonstrates that given an appropriate set of displacement fields, level of regularization, and signal strength, the transversely isotropic method can recover the relative magnitudes of all five elastic parameters without an independent measurement of stress. The quality of the reconstructions improves with increasing contrast, magnitude of deformation, and asymmetry in the distributions of material properties, indicating that elasticity imaging of cancellous bone could be a useful tool in laboratory studies to monitor the progression of damage and disease in this tissue.
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影响因子：
2.4
作者：
Odgaard, A;Kabel, J;Huiskes, R
通讯作者：
Huiskes, R
DOI：
10.3109/17453678008990819
发表时间：
1980-01-01
期刊：
ACTA ORTHOPAEDICA SCANDINAVICA
影响因子：
--
作者：
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通讯作者：
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0.9
作者：
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通讯作者：
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影响因子：
2.4
作者：
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通讯作者：
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影响因子：
3.5
作者：
Barbone, PE;Bamber, JC
通讯作者：
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