Clinical Bone Mechanics Using HR-pQCT

描述(申请人提供)：高分辨率成像的最新进展使新工具的开发成为可能，特别是微磁共振(5MR)成像和高分辨率外周定量计算机断层扫描(HR-pQCT)，这些工具承诺通过双能X射线吸收法(DXA)提供更好的总体骨强度轮廓，超过面骨密度(ABMD)。在这项应用中，我们试图确定基于图像的显微结构和5FE分析是否可以区分有椎体骨折的个体和没有脊椎骨折的个体。在我们提出的项目中，我们提出了以下假设：1.来自体外5MRI和HR-pQCT的胫骨和桡骨远端硬度和破坏载荷的形态测量和5FE预测与5CT和直接力学测试的结果高度相关，而且来自两个外围位置的参数与椎骨中的参数平行。2.5FE从活体5MR和HR-pQCT图像获得的弹性刚度和破坏载荷的估计可以更好地区分有椎体骨折的个体和没有骨折的个体，比单独使用这两种成像方法得出的微观结构测量或DXA的aBMD更好地区分。我们计划通过以下具体目标来解决上述假设：具体目标1a：在可在体内实现的信噪比和分辨率条件下进行5MRI和HR-pQCT扫描，并将以这种方式获得的骨小梁和皮质骨显微结构测量结果与高分辨率5CT获得的结果进行比较。具体目的1b：比较HR-pQCT和基于5MR图像的非线性5FE分析与基于5CT图像的5FE分析和直接力学测试所预测的胫骨远端和桡骨整个骨段的刚度和破坏载荷。具体目标2a：对与目标1a和1b中使用的胫骨远端和桡骨相同的受试者的腰椎进行5CT扫描。具体目标2b：将基于目标1a和1b中HR-pQCT和5MRI获得的成像数据的骨小梁和皮质骨微观结构测量和5FE预测与目标2a中相应椎体的5CT测量和直接机械测试进行比较。具体目标3a：将AIMS 1和AIMS 2中验证的显微结构和5FE技术应用于来自健康女性的活体5MRI和HR-pQCT扫描，并比较这两种成像方式之间的测量结果。具体目标3b：将AIMS 1和AIMS 2中验证的显微结构和5FE技术应用于两种外周成像模式，并使用研究人员实验室以前进行或目前正在进行的两项成像研究的数据，确定区分脊柱骨折受试者和未骨折同龄人的方法的有效性。

DESCRIPTION (provided by applicant): Recent advances in high-resolution imaging have permitted the development of new tools, notably micro- magnetic resonance (5MR) imaging and high-resolution peripheral quantitative computed tomography (HR- pQCT), that promise to provide a better profile of overall bone strength beyond areal bone mineral density (aBMD) by dual-energy x-ray absorptiometry (DXA). In this application, we seek to determine whether image- based microstructural and 5FE analyses can distinguish between individuals who have vertebral fractures from their counterparts without vertebral fractures. In the proposed project we advance the following hypotheses: 1. Morphological measurements and 5FE predictions of stiffness and failure load of the distal tibia and radius from ex vivo 5MRI and HR-pQCT correlate highly with those from 5CT and direct mechanical testing, and, furthermore, that parameters from the two peripheral sites parallel those in the vertebrae. 2. 5FE-derived estimates of elastic stiffness and failure load from in vivo 5MR and HR-pQCT images can differentiate between individuals with vertebral fractures from those without vertebral fractures better than microstructural measures derived by the two imaging modalities alone or aBMD by DXA. We plan to address the above hypotheses with the following specific aims: Specific Aim 1a: Perform 5MRI and HR-pQCT scans of the distal tibia and radius ex vivo under signal-to-noise and resolution conditions achievable in vivo, and compare trabecular and cortical bone microstructural measurements obtained in this manner with those from high-resolution 5CT. Specific Aim 1b: Compare the stiffness and failure load of whole bone segments of the distal tibia and radius as predicted by HR-pQCT and 5MR image-based nonlinear 5FE analyses to those predicted by 5CT image- based 5FE analysis and direct mechanical testing. Specific Aim 2a: Perform 5CT scans of lumbar vertebrae from the same subjects as the distal tibia and radius used in Aims 1a and 1b Specific Aim 2b: Compare trabecular and cortical bone microstructural measurements and 5FE predictions based on the imaging data obtained by HR-pQCT and 5MRI in Aims 1a and 1b with the 5CT measurements and direct mechanical testing of the corresponding vertebrae in Aim 2a. Specific Aim 3a: Apply the microstructural and 5FE techniques validated in Aims 1 and 2 to in vivo 5MRI and HR-pQCT scans from healthy women and compare these measurements between the two imaging modalities. Specific Aim 3b: Apply the microstructural and 5FE techniques validated in Aims 1 and 2 to the two peripheral imaging modalities and determine the effectiveness of methods in distinguishing between vertebral fracture subjects and their non-fractured peers using data from two imaging studies previously performed or currently in progress in the investigators' laboratories.