Bone Quality Assessment with a Novel Three-Bore Magnet Extremity MRI Scanner

骨质疏松症和相关的代谢性骨疾病几乎是与晚期骨质疏松症相关的普遍问题。 年龄，特别是绝经后妇女，预计到2020年每年将使社会损失超过220亿美元， 导致每年有65，000人死于骨脆性骨折。最近的研究表明 MRI可能特别适用于解决与骨质量相关的几个因素， 在患者中测量困难。高空间分辨率MRI可用于准确表征 小梁微结构，并遵循它与治疗，没有伴随的电离辐射剂量的DXA 或CT。固态MRI可以独特地非侵入性地测量有机骨基质含量，以及 矿物质质子（1H）固态MRI已被用于测量骨基质，而磷（31 P）固态MRI已被用于测量骨基质。 MRI有可能准确评估3D骨密度。将这两个测量值结合在一起， 单次同时测量可以促进对代谢性骨疾病的更多信息诊断， 特别是如果与高空间分辨率3D小梁成像相结合。 MRI是一种昂贵的测量方法，不适合用于筛查或诊断代谢性骨 疾病然而，如果核磁共振成像的成本能够大幅降低，这种测量可能会成为 在财务上与DXA竞争，同时提供显著增加的诊断信息内容， 同时完全消除电离辐射暴露。 在这个项目中，我们将开发代谢性骨病的MRI表征方法， 独特的专用廉价，紧凑，无冷冻四肢MRI扫描仪设计和建造在一个 以前的NIH资助项目。值得注意的是，这款扫描仪的磁铁设计舒适， 有效的肢体扫描，并且特别地包含三个孔：中心孔，其是在肢体扫描中的“活动”孔。 被扫描的肢体被插入其中，以及两个外围的“非活动”孔， 没有被扫描。这两个扫描仪的资本和运营成本，以及诊所的“真实的房地产”它 占用的时间大大低于典型的全身扫描仪。在撰写本文时，第二代 一个紧凑的可倾斜的磁铁与多个开口可能会到达PI的实验室开始这个项目。 具体目的是：1）进一步发展高空间分辨率的骨小梁三维MRI技术 网络结构，以及用于定量骨矿物质和基质的固态质子和磷MRI 测量; 2）评估固态MRI在体模中的这些测量的定量准确性， 动物组织和活体动物; 3）评估高空间分辨率和固体的重复性和准确性 在健康志愿者中进行MRI扫描;以及4）进行代谢性骨病患者的研究 以及年龄和性别匹配的正常人，以初步评估基于MRI的骨骼测量的准确性。 表征，并获得统计信息，将允许设计未来的临床试验。

Osteoporosis and related metabolic bone diseases are nearly universal problems associated with advanced age, particularly for postmenopausal women, expecting to cost society over $22 billion annually by 2020, and leading to 65,000 deaths each year stemming from bone fragility fractures. Recent studies have demonstrated that MRI may be of particular utility for addressing several factors related to bone quality that can only be measured with difficulty in patients. High spatial resolution MRI can be used to accurately characterize trabecular microarchitecture, and follow it with treatment, without the attendant ionizing radiation dose of DXA or CT. Solid state MRI can uniquely measure the organic bone matrix content noninvasively as well as the mineral. Proton (1H) solid state MRI has been used to measure bone matrix, while phosphorus (31P) solid state MRI has potential to accurately assess 3D bone mineral density. Combining these two measurements in a single simultaneous measurement could facilitate a more informative diagnostic for metabolic bone disease, especially if coupled with high spatial resolution 3D trabecular imaging. MRI is an expensive measurement, and not justified for screening for or diagnosing metabolic bone disease. However, if the cost of MRI could be drastically reduced, such measurements could become financially competitive with DXA while providing significantly increased diagnostic information content, and at the same time completely eliminating ionizing radiation exposure. In this project, we will develop the methodology of MRI characterization of metabolic bone disease using a unique dedicated inexpensive, compact, cryogen-free extremity MRI scanner designed and constructed in a previous NIH-funded project. Notably, the magnet of this scanner has been designed for comfortable and efficacious extremity scanning, and in particular contains three bores: a central bore that is the “active” bore in which the limb being scanned is inserted, and two peripheral “nonactive” bores that comfortably accept the leg not being scanned. Both the capital and operating costs of this scanner, as well as the clinic “real estate” it occupies, are drastically lower than for the typical whole body scanner. As of this writing, a second generation compact tiltable magnet with multiple openings may arrive in the PI's lab by the beginning of this project. The specific aims are: 1) Further the technical development of high spatial resolution 3D MRI of trabecular network architecture, and solid state proton and phosphorus MRI for quantitative bone mineral and matrix measurement; 2) Assess the quantitative accuracy of solid state MRI for these measurements in phantoms, animal tissues, and live animals; 3) Evaluate the repeatability and accuracy of high spatial resolution and solid state MRI scanning in healthy volunteer subjects; and 4) Carry out studies of metabolic bone disease patients and age- and gender-matched normals to make a preliminary assessment of the accuracy of MRI-based bone characterization, and to acquire statistical information that will permit the design of future clinical trials.