Ultrasound measurements of the calcaneus: effects of ethnicity

This study investigated whether there were differences in quantitative ultrasound (QUS) of the calcaneus between African-American and Caucasian females. QUS-1X, an ultrasonometer by Metra Biosystems Inc., was used to determine broadband ultrasound attenuation (UBI-4) using Burg Spectral Estimation in decibels/megahertz. The average transit time through the heel (TTH) in microseconds was used to estimate bone size. A multiple factor index taking into account bone size, UBI-4T, was calculated by dividing UBI-4 by TTH in decibels/(Megahertz x microseconds). Results showed that premenopausal Caucasian females (n = 37) have approx 6-8% lower values (p < 0.05) of QUS indices than their African-American (n = 54) counterparts. However, after adjusting for bone size, the differences in attenuation disappeared. Pilot data for males (Caucasian: n = 16, African-American: n = 18) suggest that the differences in QUS appear to be related to bone size. The limited scope of our study supports the fact that there are differences in QUS between premenopausal Caucasian and African-American females, but not with the same magnitude as evidenced by dual X-ray absorptiometry. We recommend that more data be collected on ethnic differences across all age ranges, to help understand how QUS may be used to assess bone mass and determine its value either as a screening tool to diagnose low bone mass or as a tool to predict osteoporotic fracture within various ethnic groups.