Measurements of postmenopausal bone loss with a new contact ultrasound system

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Abstract
Measurements of broadband ultrasonic attenuation (BUA) and velocity of ultrasound through the heel (heel velocity, HV) were performed with a Contact Ultrasonic Bone Analyzer (CUBA-Research model) in 229 women. The subjects consisted of 16 healthy young volunteers (Group 1, mean age 26 years), 170 healthy pre- and postmenopausal women (Group 2, mean age 53 years), and 43 osteoporotic women with radiographically defined vertebral crush fracture (Group 3, mean age 66 years). Subjects in Group 1 had 10 repeated measurements in a study of short-term precision. Women in Groups 2 and 3 also had dual X-ray absorptiometry (DXA) scans to measure lumbar spine and femoral neck bone mineral density (BMD). The BUA and HV measurements for all 229 women showed a significant correlation (r = 0.75,P < 0.001). The precision study on the subjects in Group 1 gave a root mean square coefficient of variation of 6.3% for BUA and 1.04% for HV. Linear regression analysis gave the following relationship between BUA and age for the 170 normal women in Group 2: BUA = 83.6 − 0.86 (age 40) dB/MHz (r = −0.31,P < 0.001, SEE = 16.3 dB/MHz). The relationship between HV and age was as follows: HV = 1614 − 2.3 (age 40) m/s (r = −0.33,P < 0.001, SEE = 42 m/s). Multivariate regression analysis showed that in addition to age, years since the menopause was also a significant factor in determining both BUA and HV. In the first 5 years following the menopause, BUA and HV decreased by 2.2% and 0.3%/year, respectively, whereas in the next 10 years the rates of decrease fell to 0.5% and 0.03%/year. The BUA and HV measurements on the 43 osteoporotic subjects in Group 3 gave mean T-scores of −2.1 and −1.9 compared with 59 premenopausal women, and mean Z-scores of −1.3 and −0.9 compared with 26 age-matched normal women in Group 2, respectively. In comparison, the lumbar spine and femoral neck DXA measurements in the same subjects gave mean T-scores of −2.9 and −2.1 and mean Z-scores of −1.7 and −1.0, respectively. Lumbar spine BMD gave the best discrimination between women with osteoporotic vertebral fractures and normal subjects. However, the difference between the lumbar spine and BUA Z-scores was not statistically significant. Femoral neck BMD was equivalent to the ultrasound parameters in T-score and Z-score values.