Dual energy x-ray absorptiometry and quantitative ultrasound are not interchangeable in diagnosing abnormal bones
Archives of Diseases in Childhood, 05/14/2012
Williams JE et al. – Dual energy x–ray absorptiometry (DXA) and quantitative ultrasound (QUS) identify different individuals as ‘abnormal’. Agreement between bone mineral density (BMD) and tibia SOS is lower in obese subjects. Without a gold–standard, it is difficult to determine which technique is more ‘correct’.
Methods- 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.
