Childhood Nutrition Research Centre, UCL Institute of Child Health, University College London, 30 Guilford St., London, UK.
Arch Dis Child. 2012 Sep;97(9):822-4. doi: 10.1136/archdischild-2011-301326. Epub 2012 May 1.
To evaluate whether dual energy x-ray absorptiometry (DXA) and quantitative ultrasound (QUS) classify the same children as 'abnormal' (SD (z) score (SDS) ≤-2).
Speed of sound (SOS) was measured at the radius and tibia using QUS and lumbar spine bone mineral density (BMD) using DXA in 621 subjects aged 5-20 years; healthy 412, cystic fibrosis 117 and obese 92.
BMD SDS positively (p<0.001) and tibia SOS SDS negatively correlated with size (p<0.05). Disagreement between DXA and QUS for 'abnormal' scans occurred in 6-31%. Those with abnormal BMD and normal SOS SDS had lower mean BMI SDS than those with normal BMD and abnormal SOS SDS. SOS measurements were unobtainable in some children, especially in the obese group.
DXA and QUS identify different individuals as 'abnormal'. Agreement between BMD and tibia SOS is lower in obese subjects. Without a gold-standard, it is difficult to determine which technique is more 'correct'.
评估双能 X 射线吸收法（DXA）和定量超声（QUS）是否将相同的儿童归类为“异常”（SD（z）评分（SDS）≤-2）。
在 621 名 5-20 岁的受试者中使用 QUS 测量桡骨和胫骨的声速（SOS），并使用 DXA 测量腰椎骨密度（BMD）；健康组 412 名，囊性纤维化组 117 名，肥胖组 92 名。
BMD SDS 与大小呈正相关（p<0.001），胫骨 SOS SDS 与大小呈负相关（p<0.05）。DXA 和 QUS 对“异常”扫描的结果存在 6-31%的不一致。那些 BMD 异常但 SOS SDS 正常的患者的平均 BMI SDS 低于那些 BMD 正常但 SOS SDS 异常的患者。在一些儿童中，特别是在肥胖组中，无法进行 SOS 测量。
DXA 和 QUS 识别出不同的“异常”个体。肥胖患者中 BMD 和胫骨 SOS 的一致性较低。由于没有金标准，很难确定哪种技术更“正确”。
