Quantitative ultrasound of the calcaneus - An in vivo comparison with dual-energy X-ray absorptiometry and magnetic resonance imaging

This study was performed in a clinical setting and aimed to evaluate the relationship between quantitative ultrasound (QUS) of the calcaneus with bone mineral density (BMD) assessed with dual-energy X-ray absorptiometry (DXA) and with variables derived from magnetic resonance imaging (MRI). Thirty-two post menopausal women (mean age 61 yr) were studied at the level of the nondominant calcaneus. QUS was performed using a DTU-one device, including parametric imaging and yielded speed of sound (SOS) and broad-band ultrasound attenuation (BUA) data. DXA was performed at a matched region of interest (ROI) in the calcaneus, using a Hologic QDR 4500 device. MRI, also performed at a matched ROI, yielded, using a Siemens Magnetom Vision device, the inverse of the transverse relaxation time (1/T-2*) and the phase standard deviation (PSD). The strongest relationship between QUS and the other variables involved BUA and BMD (r = 0.677, p < 0.001); 1/T-2* showed a trend to correlation with SOS (r = 0.359, p = 0.044) and with BMD (r = 0.364, p = 0.040), whereas the relationship between 1/T-2* and BUA, PSD and BUA, PSD and SOS, and PSD and BMD remained far from significant. Regression analysis of QUS, DXA, and MRI variables versus age showed a trend to significant decline only for 1/T-2* (r= -0.409, p = 0.020). In conclusion, this study shows that BUA of the calcaneus has the best correlation with BMD, and that, at least in a clinical setting, the ability of QUS to give information about bone structure is limited.