Comparison of quantitative ultrasound of the phalanges with conventional bone densitometry in healthy postmenopausal women

The objective of this study was to evaluate the utility of the quantitative ultrasound (QUS) technique for the identification of subjects with spine fracture or low bone mineral density (BMD) previously determined by dual energy X-ray absorptiometry (DEXA). QUS of the phalanges in 1,350 postmenopausal women (60-83 years old) was compared with DEXA measurements of four skeletal sites (lumbar spine, total hip, femoral neck, and distal radius) of the same subjects. The contribution of body mass index (BMI) was also assessed. Amplitude dependent speed of sound (AD-SoS), ultrasound bone profile index (UBPI), and BMD of all anatomical regions, except for the spine, decreased significantly with increasing age quartiles. QUS parameters correlated weakly but significantly with BMD ( r =0.21-0.31, p < 0.01). After adjustment for BMI, the association between QUS parameters and BMD remained unchanged. UBPI was found to be independent of BMI. All techniques and all sites were able to significantly discriminate fractured from non-fractured subjects by receiver operating characteristic (ROC) analysis (area under the curve [AUC]>= 0.60, p < 0.0001). AD-SoS and UBPI showed similar fracture discrimination ability of spine, distal radius and total body BMD in terms of odds ratios, but BMD of the total hip and femoral neck showed the best performance in discriminating fractured from non-fractured subjects. In conclusion, QUS assessment of the phalanges correlates moderately with BMD of all skeletal sites and is able to effectively discriminate fractured from non-fractured subjects.