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的事件。在受伤的一年内，20%-30%的患者死亡，50%的患者失去行走能力；在美国，这些骨折占每年骨折治疗直接成本的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女性没有资格接受骨质疏松症治疗，目前的标准是基于双能X射线骨密度仪(DXA)测量的骨密度(BMD)。因此，需要一种更好的方法来确定个人是否有跌倒导致髋部骨折的风险。从生物力学上讲，如果跌倒产生的冲击力大于骨骼强度，髋部就会骨折。因此，确定髋关节力量的能力对于骨折风险评估至关重要。目前最好的无创直接髋关节力量评估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)不足以分辨髋部的骨微结构。利用我们最近的工作，我们建议开发一种新的方法，使用磁共振成像(MRI)和生物力学相结合的方法来评估活体髋关节力量。首先，我们建议优化我们现有的用于微结构髋关节成像的MRI方案，以达到0.23-0.5 mm的空间分辨率，并将有限元计算时间减少到30分钟以下，以便在台式计算机上模拟跌落到髋部上来预测髋关节力量。其次，我们建议通过将我们的MRI衍生的髋关节力量技术获得的值与从30名捐赠者获得的身体股骨力学测试的黄金标准技术获得的值进行比较，来验证该技术的准确性。第三，我们建议应用上面优化和验证的方法来确定与匹配的健康对照组(N=40)相比，髋部骨折(N=40)患者跌落到髋部时是否具有较低的骨强度。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强度的重测再现性。如果在纵向研究中得到进一步验证，该项目下提出的基础工作有可能在评估髋部骨折风险和监测骨质疏松症治疗效果方面引入一种范式转变。

 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.