Dual-energy X-ray Absorptiometry
Dual-energy X-ray Absorptiometry
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DOI：
10.1016/j.jocd.2017.06.014
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发表时间：
2017-07-01
影响因子：
2.5
通讯作者：
Vokes, Tamara
中科院分区：
文献类型：
--
作者：
Jain, Rajesh K.;Vokes, Tamara
用双能X线骨密度仪(DXA)测量骨密度(BMD)是评估骨折风险最常用的方法。DXA使用两种不同的能量X射线来计算BMD，并与年轻的标准数据库进行比较，计算T分数。1994年，世界卫生组织根据T-Score定义了骨质疏松症，改变了该领域的范式，永远将DXA测量置于骨质疏松症诊断的中心。从那时起，许多大型研究已经证明了DXA对BMD的预测价值--BMD每下降一个标准差，骨折的相对风险就有1.5-2.5倍。这种预测能力类似于血压预测心肌梗死。DXA的局限性也是需要考虑的重要因素。虽然DXA的BMD可以识别出有风险的人，但愿意和不愿意骨折的患者的BMD有显著的重叠。在男子和少数族裔群体中也需要特别考虑。这些组可能有不同的骨大小，从而影响骨密度的正常范围，和/或不同的骨结构，影响骨密度与骨折之间的关联。最后，BMD可能会受到定位错误或人工制品的影响，包括骨关节炎、骨折和珠宝。当然，DXA也有巨大的优势--即它的广泛可用性、低辐射暴露以及大量将DXA测量与骨折风险联系起来的证据。由于这些原因，DXA仍然是目前和可预见的未来骨折评估的基石。
Bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry (DXA) is the most commonly used method to assess fracture risk. DXA utilizes two different energy X-rays to calculate BMD and, by comparison to a young normative database, the T-score. In 1994, the World Health Organization defined osteoporosis based on T-score, changing the paradigm of the field and forever placing DXA measurements in the center of osteoporosis diagnosis. Since then, many large studies have demonstrated the predictive value of BMD by DXA-for every standard deviation decline in BMD, there is a relative risk of 1.5-2.5 for fracture. This predictive ability is similar to how blood pressure can predict myocardial infarction.Limitations of DXA are also important to consider. While BMD by DXA can identify those at risk, there is a significant overlap in the BMD of patients who will and will not fracture. Special considerations are also needed in men and ethnic minority groups. These groups may have different bone size, thus affecting the normative range of BMD, and/or distinct bone structure that affect the association between BMD and fractures. Finally, BMD can be affected by positioning errors or artifacts, including osteoarthritis, fracture, and jewelry. Of course, DXA has tremendous strengths as well-namely its wide availability, its low radiation exposure, and a large body of evidence that relate DXA measurements to fracture risk. For these reasons, DXA remains the cornerstone of fracture assessment now and for the foreseeable future.