Comparison of ultrasound and bone mineral density assessment of the calcaneus with different regions of interest in healthy early menopausal women

This study investigated the effect of different sized regions of interest ( ROIs) on quantitative ultrasound (QUS) variables of the calcaneus. The effe ct on QUS of using a fixed ROI as opposed to an ROI adjusted for foot lengt h was also assessed. Eighty Caucasian women, aged 50-57 yr (mean 53 +/- 2) who were healthy and within 0.5-5 yr of the onset of menopause participated in this study. Using the QUS-1(TM) Ultrasonometer (Metra Biosystems, Mount ain View, CA), we assessed broadband ultrasound attenuation ([BUA] and UBI- 4, dB/MHz), the average transit time through the heel ([TTH], mu s) and a m ultiple-factor index (UBI-4T = UBI-4/TTH, dB/[MH.mu s]). The QUS measuremen t results were calculated from three different sizes of ROI as well as one in a fixed location and one adjusted for foot size. Bone thickness, bone wi dth, bone mineral content ([BMC], g/cm), bone mineral density area ([BMDa], g/cm(2)), and bone mineral density volume ([BMDv], g/cm(3)) were measured by single-energ photon absorptiometry. Lateral radiography of the foot was used to ensure the QUS scanning location in a subgroup. The results showed that there was a 1.4-5.9% difference in QUS parameters among different ROIs (p = 0.076-0.001). No significant differences between fixed and adjusted l ocation were found regarding the mean values of QUS. The correlation betwee n the fixed and adjusted locations was very strong, although there was a 12 -42% unexplained variation. On the other hand, QUS in the size-adjusted ROI increased the correlation with BMC/BMD compared to the fixed QUS assessmen ts. After controlling for body weight and height, a significant correlation between QUS and bone mass variables remained, and in some cases correlatio ns became stronger. Lateral radiography showed that when using a fixed loca tion to scan a large foot, the scanning area might be close to the bone edg e, an area of higher BMD and potential acoustic artifacts. When scanning a small foot, the scanning area was confined to the middle of the calcaneus. Our results indicate that bone size has a modest effect on BUA. There is a better correlation with BMD when the measurement region is appropriately lo cated in the calcaneus. This suggests that measurement location based on fo ot size may improve the accuracy of the measurements, resulting in good dia gnostic sensitivity.