3-D Visualization and Prediction of Spine Fractures

描述（由申请人提供）：椎体骨折是最常见的骨质疏松性骨折类型，大约三分之一的女性和六分之一的男性在50岁以上。尽管它们的发病率很高，但对椎体骨折风险的敏感和具体估计仍然难以捉摸。这在很大程度上是由于目前估计椎体强度的方法准确度和精密度有限。骨密度（BMD）的平均测量只能解释50-70%的椎体强度差异，考虑到整个椎体骨组织的不均匀分布，这一结果并不令人惊讶。越来越多的令人信服的证据表明，这种异质性在控制椎体力学行为方面的重要性。定量计算机断层扫描（QCT）的最新进展允许对整个骨骼的骨密度分布甚至小梁各向异性进行无创测量。我们建议这些额外的测量可以用来建立临床评估椎体骨折风险的新标准。我们的总体假设是，基于CT的方法考虑了密度的不均匀分布和整个椎体的小梁各向异性，比仅基于平均骨密度的方法更准确地预测了椎体强度。提出了四个具体目标。目的1将检验基于ct的椎体内密度异质性测量是否为椎体强度的独立预测因子。目标#2-#4是紧密结合的实验和计算研究，将测试在基于qct的椎体有限元（FE）模型中纳入样本特异性、各向异性材料特性的重要性。这些研究将调查这种材料属性分配对椎体强度和破坏行为的有限元预测准确性的影响。Aim #2将使用微有限元分析来量化整个椎体的各向异性弹性特性。Aim #3将使用Aim #2中获得的材料特性进行基于qct的有限元分析，也使用纯粹基于BMD或BMD和小梁各向异性的估计确定的特性。FE预测椎体力学行为的准确性将通过Aim #4中的实验进行评估。这些实验将使用我们在过去几年中开发的三维故障可视化技术。这些技术为我们提供了独特的能力来评估的保真度与有限元模型预测骨强度，以及真实的变形和破坏行为的椎体。这种评估对于衡量这些模型的性能、确定改进其预测的方法以及使其在临床领域得到广泛实施至关重要。综上所述，拟议的研究构成了一组具体和重要的步骤，朝着我们的长期目标发展技术，通过临床可行的测量来高度准确地预测患者的脊椎强度。因此，这项工作在更好地诊断、治疗和预防脊柱骨折方面具有很强的潜力。公共卫生相关性。50岁以上的人中，三分之一的女性和六分之一的男性将在他们的余生中遭受脊柱骨折。这个项目的重点是开发更准确地预测脊柱骨强度的方法。

DESCRIPTION (provided by applicant): Vertebral fractures are the most common type of osteoporotic fracture, afflicting approximately one in three women and one in six men over the age of 50. Despite their high prevalence, sensitive and specific estimates of vertebral fracture risk have remained elusive. This is due in large part to the limited accuracy and precision of current methods of estimating vertebral strength. Average measures of bone mineral density (BMD) explain only 50-70% of the variance in vertebral strength, a result that is not surprising given the heterogeneous distribution of bone tissue throughout the vertebra. A growing and compelling amount of evidence points to importance of this heterogeneity in governing the mechanical behavior of the vertebra. Recent advances in quantitative computed tomography (QCT) allow non-invasive measurement of the distribution of bone density and even trabecular anisotropy in whole bones. We propose that these additional measurements can be used to establish a new standard for clinical evaluation of vertebral fracture risk. Our overall hypothesis is that CT- based methods that account for the heterogeneous distribution of density and trabecular anisotropy throughout the vertebra provide more accurate predictions of vertebral strength than do methods based solely on average BMD. Four specific aims are proposed. Aim #1 will test whether CT-based measures of the intra-vertebral heterogeneity in density are independent predictors of vertebral strength. Aims #2-#4 are closely coupled experimental and computational studies that will test the importance of incorporating specimen-specific, anisotropic material properties in QCT-based finite element (FE) models of the vertebra. These studies will investigate the effect of this material property assignment on the accuracy of the FE predictions of vertebral strength and failure behavior. Aim #2 will use micro-finite element analysis to quantify the anisotropic elastic properties throughout the centrum. Aim #3 will carry out the QCT-based FE analyses using the material properties obtained in Aim #2 and also using properties determined purely from estimates based on BMD or on BMD and trabecular anisotropy. The accuracy of the FE predictions of vertebral mechanical behavior will be evaluated through experiments performed in Aim #4. These experiments will use 3-D failure visualization techniques that we have developed over the past several years. These techniques afford us the unique ability to assess the fidelity with which the FE models predict bone strength as well as the true deformation and failure behavior of the vertebra. Such assessment is critical for gauging the performance of these models, for identifying means of improving their predictions, and for enabling their widespread implementation in the clinical arena. Taken together, the proposed studies constitute a set of concrete and consequential steps towards our long-term goal of developing techniques for highly accurate, patient-specific predictions of vertebral strength from clinically feasible measurements. As such, this work has strong potential for leading the way to better diagnosis, treatment, and prevention of spine fractures. PUBLIC HEALTH RELEVANCE. One in three women and one in six men over age 50 will suffer a spine fracture in their remaining lifetime. This project focuses on developing methods for obtaining more accurate predictions of bone strength in the spine.