Relationships of ultrasonic backscatter with ultrasonic attenuation, soundspeed and bone mineral density in human calcaneus

Ultrasonic attenuation and sound speed have been investigated in trabecular bone by numerous authors. Ultrasonic backscatter has received much less at tention, To investigate relationships among these three ultrasonic paramete rs and bone mineral density (BMD), 30 defatted human calcanei were investig ated in vitro. Normalized broadband ultrasonic attenuation (nBUA), sound sp eed (SOS), and logarithm of ultrasonic back-scatter coefficient (LBC) were measured. Bone mineral density was assessed using single-beam dual energy x -ray absorptiometry (DEXA). The correlation coefficients of least squares l inear regressions of the three individual ultrasound (US) parameters with B MD were 0.84 (nBUA), 0.84 (SOS) and 0.79 (LBC). The 95% confidence interval s for the correlation coefficients were 0.69-0.92 (nBUA), 0.68-0.92 (SOS) a nd 0.60-0.90 (LBC). The correlations among pairs of US variables ranged fro m 0.63-0.79. Variations in nBUA accounted for r(2) = 62% of the variations in LBC. Variations in SOS accounted for r(2) = 40% of the variations in LBC . These results suggest that ultrasonic backscattering properties may conta in substantial information Rot already contained in nBUA and SOS. A multipl e regression model including all three US variables was somewhat more predi ctive of BMD than a model including only nBUA and SOS. (C) 2000 World feder ation for Ultrasound in Medicine & Biology.