Clinical Assessment of Hip Fracture Biomechanics using MRI

 描述（由申请人提供）：髋部骨折是一种毁灭性事件。在受伤后的一年内，20-30%的患者死亡，50%的患者失去行走能力;在美国，这些骨折占骨折护理直接年度费用的70%（120亿美元）。具有讽刺意味的是，根据目前的标准，超过一半的髋部骨折妇女不符合骨质疏松症治疗的条件，目前的标准是基于双能X射线吸收测定法（DXA）测量的骨矿物质密度（BMD）。因此，需要一种更好的方法来确定一个人是否有跌倒导致髋部骨折的风险。从生物力学上讲，如果跌倒造成的冲击力大于骨骼强度，髋关节就会骨折。因此，确定髋关节强度的能力对于骨折风险评估至关重要。目前用于直接髋关节强度评估的最佳无创工具是基于定量计算机断层扫描（QCT）引导的有限元模型。然而，由于电离辐射剂量的限制，临床QCT的空间分辨率（0.6-1 mm）不足以分辨髋关节的骨微结构。利用我们最近的工作，我们建议开发一种新的方法来评估髋关节强度在体内使用磁共振成像（MRI）加上生物力学。首先，我们建议优化我们目前的MRI协议的微观结构髋关节成像，以实现0.23-0.5 mm的空间分辨率，并减少有限元计算时间小于30分钟，用于预测髋关节强度模拟跌倒在一台台式电脑上的髋关节。其次，我们建议通过比较该技术获得的值与从30个供体获得的尸体股骨机械测试的金标准技术获得的值来验证我们的MRI衍生髋关节强度技术的准确性。第三，我们建议应用上述优化和验证的方法，以确定髋部骨折患者（N=40）与匹配的健康对照组（N=40）相比，髋部跌倒时的骨强度是否较低。我们还建议通过在10名健康受试者中重复扫描和分析来确定MRI衍生强度的重测重现性。如果在纵向研究中得到进一步验证，本项目下提出的基础有可能引入评估髋部骨折风险和监测骨质疏松症治疗疗效的范式转变。

 DESCRIPTION (provided by applicant): Hip fracture is a devastating event. Within a year of the injury, 20-30% of patients die and 50% lose the ability to walk; in the United States these fractures account for 70% ($12 billion) of the direct annual costs of fracture care. Ironically, more than half of the women who sustain a hip fracture would not have qualified for osteoporosis treatment by the current criteria, which are based on bone mineral density (BMD) measurements by dual energy X-ray absorptiometry (DXA). Thus, a better approach is needed to determine if an individual is at risk for hip fracture from a fall. Biomechanically, a hip will fracture if the impact force resulting from a fall is greater than the bone strength. Therefore, th ability to determine hip strength is critical for fracture risk assessment. The current best non-invasive tool for direct hip strength assessment is based on quantitative computed tomography (QCT) guided finite element models. However, due to ionizing-radiation dose restrictions, the spatial resolution of clinical QCT (0.6-1 mm) is not sufficient to resolve bone microstructure at the hip. Leveraging our recent work, we propose to develop a novel method for assessing hip strength in vivo using magnetic resonance imaging (MRI) coupled with biomechanics. First, we propose to optimize our current MRI protocol for microstructural hip imaging to achieve 0.23-0.5 mm spatial resolution, and to reduce the finite element computation time to less than 30 minutes for predicting hip strength simulating a fall onto the hip on a desktop computer. Second, we propose to validate the accuracy of our MRI-derived hip strength technique by comparing the values obtained by this technique to the values obtained from the gold standard technique of mechanical testing of cadaveric femurs obtained from 30 donors. Third, we propose to apply the method optimized and validated above to determine if patients with hip fracture (N=40) have low bone strength for a fall onto the hip compared to matched healthy controls (N=40). We also propose to determine the test-retest reproducibility of MRI-derived strength by repeating the scanning and analysis in 10 healthy subjects. If further validated in longitudinal studies, the groundwork proposed under this project has the potential to introduce a paradigm shift for assessing hip fracture risk and monitoring the efficacy of osteoporosis treatment.