Can ultrasound be used to estimate bone mineral density in children with growth problems?

AIM: To assess predictability of bone mineral density (BMD) of the lumbar spine (LS) determined by dual-energy x-ray absorptiometry (DXA) using by ultrasound speed of sound of the right and left radii (SOS-R and SOS-L) in patients with growth problems.
METHODS: Ultrasound and DXA were compared in patients with advanced, normal and delayed bone ages assessed by Greulich and Pyle (GP) and Tanner and Whitehouse (TW3) methods.
RESULTS: There was a strong correlation (r), of raw scores, between SOS-R and SOS-L, r = 0.81, p = 0.000 and their respective Z-scores, r = 0.78, p = 0.000. Z-score correlations were poor between SOS-R or SOS-L and LS-BMD. Sensitivity, specificity, positive and negative predictive values of SOS-R and Z-scores for predicting normal (>-1 to <1) and low (<-1) LS-BMD were poor. For high (>1) LS-BMD, Z-scores were 22%, 93%, 29% and 90%, respectively, for SOS-R and for SOS-L, 25%, 89%, 20% and 91%. For very low (<-2) LS-BMD, SOS-R and SOS-L were the same, respectively, 29%, 91%, 40% and 86%.
CONCLUSION: Ultrasound of the radius is a poor predictor of radiologically assessed BMD at the LS, especially with delayed bone age. ©2013 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.