Comparison of broadband ultrasound attenuation to single X-ray absorptiometry measurements at the calcaneus in postmenopausal women.

Broadband ultrasound attenuation (BUA), a radiation-free and portable technology, may be useful in assessing bone density and fracture risk. In this study, we compared cross-sectional BUA measurements to the more established single energy X-ray absorptiometry measurements of bone mineral density (BMD) at the calcaneus in 259 healthy postmenopausal women, aged 45-76 years. Paired measurements with repositioning of the subject's dominant heel were made consecutively by each method. A coefficient of variation (CV) for each method was calculated for each individual from the paired scans. BUA and BMD of the heel were also compared with BMD of the lumbar spine and femoral neck, as measured by dual energy X-ray absorptiometry. BUA was significantly correlated with BMD at the calcaneus (r = 0.66, P < 0.01). Heel BUA was also correlated with lumbar spine BMD (r = 0.43, P < 0.01) and femoral neck BMD (r = 0.43, P < 0.01) but the correlations were lower than those between heel BMD and spine (r = 0.63, P < 0.01) or femoral neck BMD (r = 0.62, P < 0.01). The mean CV for heel BUA (3.60 +/- 3.50%) was significantly greater than that for heel BMD (1.06 +/- 0.99%, P < 0.01). The moderate correlation of calcaneal BUA and BMD, the lower correlations of BUA than heel BMD with both spine and hip BMD, and lower precision of BUA indicate BUA does not predict bone density as effectively as absorptiometry, the current standard methodology.