Ultrasound measurements in the calcaneus: Precision and its relation with bone mineral density of the heel, hip, and lumbar spine

Broadband ultrasound attenuation (BUA) and speed of sound (SOS) in the heel are suggested to measure bone density and structure and to predict fracture risk. Short-term precision (five consecutive measurements in 1 h) and longterm precision (six within 3 months) of ultrasound parameters were studied in 20 healthy subjects. The coefficient of variation (CV) did not change over a 3-month period for SOS (1.3%). Short-term precision of BUA was 3.4% (CV) and long-term precision was 4.9% (CV) (not significantly different: p = 0.09). Relationships between ultrasound parameters and BMD at various sites were examined in 42 subjects. BMD at the heel was assessed at the location corresponding to that of the ultrasound measurements (BMD heel). Correlation coefficients, corrected for imprecision in the measurements, for BUA and SOS vs. BMD heel, were 0.81 and 0.76, respectively. The correlation coefficients between heel measurements (BUA, SOS, and BMD heel) and BMD in the hip and lumbar spine ranged from 0.37 to 0.57. The relationships between BUA, SOS, and BMD heel vs. BMD of the hip were modified by physical activity and body weight. Higher physical activity and body weight were associated with higher BMD values at the hip. BUA values