Improving the Accuracy of Pediatric DXA Bone Studies

描述（由申请人提供）：可用性、易用性、相对低的成本、准确性和再现性使双能X射线吸收测定法（DXA）成为全球最广泛使用的技术，用于在成人人群中获得研究和临床目的的骨测量。然而，与生长和成熟相关的误差大大降低了DXA骨测量在儿科人群中的价值。一些研究人员发现，儿童骨质疏松症经常被误诊继发于DXA扫描的结果。在这方面，国际临床密度测定学会的官方立场指出，其最近的建议是，根据DXA标准，年龄<20岁的受试者不应被诊断为骨质疏松症。尽管如此，人们越来越认识到骨质疏松症有其在儿童时期的前身，并要求检查骨收购和治疗的儿童患者人群的反应强调迫切需要优化DXA测量儿童。 该提案的具体目的是通过评估和校正儿童和年轻人中轴骨骼中骨骼形状、骨骼大小、脂肪和肌肉体积和分布对DXA测量的影响来提高DXA测量的准确性。将通过计算机断层扫描（CT）确定椎体骨密度，并通过磁共振成像（MRI）评估儿童和成人的腰椎体、腹部脂肪和棘旁肌和腹部肌肉组织的体积。基于从MRI和CT收集的数据，我们将能够开发和验证性别和年龄特定的公式，这些公式将校正骨骼大小和身体成分对DXA测量的影响。将这些校正因子纳入当前和未来的DXA设备将大大提高其骨测量的准确性。此外，将检查骨龄和体格检查（坦纳分期、身高、坐高、体重、BMI、腹径、腰围、臀围、腰/臀比和皮褶测量值）的结果与DXA值之间的关系，以尝试确定哪些临床参数可用于优化DXA骨测量。

DESCRIPTION (provided by applicant): Availability, ease of use, relative low cost, accuracy and reproducibility have made dual energy x-ray absorptiometry (DXA) the most widely used technique worldwide to obtain bone measurements for both research and clinical purposes in adult populations. However, errors related to growth and maturity greatly diminish the value of DXA bone measurements in pediatric populations. Several investigators have found that osteoporosis in children is frequently misdiagnosed secondary to results from DXA scans. In this regard, the official position of the International Society for Clinical Densitometry states its recent recommendations that subjects <20 years of age should not be diagnosed with osteoporosis based on DXA criteria. Nevertheless, the increased awareness that osteoporosis has its antecedents in childhood and the demand for examinations of bone acquisition and response to therapy in pediatric patient populations stress the urgent need to optimize DXA measurements for children. The specific aims of this proposal are to improve the accuracy of DXA measurements by assessing and correcting for the influence of bone shape, bone size, and fat and muscle volume and distribution on DXA measurements in the axial skeleton of children and young adults. Vertebral bone density will be determined by computed tomography (CT), and the volumes of the lumbar vertebral bodies, abdominal fat and paraspinous and abdominal musculature in children and adults will be assessed by magnetic resonance imaging (MRI). Based on the data collected from MRI and CT, we will be able to develop and validate sex- and age-specific formulas that will correct for the influence that bone size and body composition has on DXA measurements. The incorporation of these correction factors into current and future DXA equipment will greatly improve the accuracy of their bone measurements. In addition, the relationships between outcomes from bone age and physical examinations (Tanner stage, height, sitting height, weight, BMI, abdominal diameter, waist circumference, hip circumference, waist/hip ratio and skin fold measurements) and DXA values will be examined in an attempt to establish which clinical parameter(s) can be used in the optimization of DXA bone measurements.