Osteoporotic biopsies assessed by microCT

描述(由申请人提供)： 骨质疏松症传统上被定义为多孔性骨结构，其数量减少，但具有正常的骨材料或质量。骨密度降低被认为是骨质疏松症的标志，但骨折是关键的临床结果。此外，尽管骨密度与骨的力学特性有关，但它并不能完全解释骨的力学反应。越来越多的证据表明，骨周转不仅通过影响骨量，还通过影响建筑、矿物质和基质质量来影响骨强度的变化。定量显微计算机断层扫描(MicroCT)可以在三维上表征松质骨的数量和质量，并探讨骨质疏松和骨转换的影响。这项探索性和发展性拨款提案(R21)的目标是使用定量显微CT分析人类活检组织。以正常、低周转率骨质疏松和高周转率骨质疏松症为特征的髂骨活组织检查将检验以下研究问题：正常、低周转率和高周转率骨质疏松骨之间松质体积分数、骨小梁三维结构和材料不均匀模式是否有所不同？将低周转率或高周转率骨质疏松症患者的髂骨活检组织与正常组织标本进行定量显微CT比较。将描述骨体积分数和骨小梁结构。定量CT X射线衰减值将用于提供骨小梁内的组织矿物质密度。组织矿物质密度的变化将通过距离变换方法作为距离小梁表面深度的函数来评估。将在三组之间进行比较，以调查低转换率和高转换率的骨之间以及骨质疏松和对照标本之间是否存在实质性差异。主要目的是检测不同周转状态下骨小梁结构和材料特性的差异。这些结果应该导致关于骨质疏松症患者和可能在治疗干预下的周转率对骨质量的影响的具体假设。

DESCRIPTION (provided by applicant): Osteoporosis has been defined traditionally as porous bone structure that is reduced in quantity but has normal bone material or quality. A decrease in bone density is considered the hallmark of osteoporosis, but bone fracture is the critical clinical outcome. Moreover, although bone density is associated with the mechanical characteristics of bone, it does not fully account for bone mechanical response. There is a growing body of evidence that bone turnover contributes to changes in bone strength by affecting not only quantity but also architecture, mineral, and matrix quality. Quantitative micro-computed tomography (microCT) has the potential to characterize the quantity and quality of cancellous bone in three dimensions and to explore the effects of osteoporosis and bone turnover. The goal of this exploratory & developmental grant proposal (R21) is to analyze human biopsies using quantitative microCT. Iliac crest biopsies characterized as normal, low-turnover osteoporosis, and high-turnover osteoporosis will be examined to test the following research question: Do cancellous volume fraction, trabecular three-dimensional architecture, and patterns of material inhomogeneity differ among normal, low-turnover, and high-turnover osteoporotic bone? Human iliac crest biopsies of low-turnover or high-turnover osteoporosis will be compared with normal biopsies by quantitative microCT. Bone volume fraction and trabecular architecture will be characterized. Quantitative CT x-ray attenuation values will be used to provide tissue mineral density within trabeculae. The variation in tissue mineral density will be assessed as a function of depth from the trabecular surface by a distance transformation approach. Comparisons will be made among the three groups to investigate whether substantial differences exist between low- and high-turnover bone and between osteoporotic and control specimens. The main goal is to detect differences in trabecular architecture and material properties with turnover state. These results should lead to specific hypotheses about the effects of turnover rate on bone quality in osteoporosis and possibly under therapeutic interventions.