Ability of ultrasound backscattering to predict mechanical properties of bovine trabecular bone.

Ultrasound (US) backscatter measurements have been proposed for the quantitative evaluation of bone quality. In this study, we explored the ability of broadband US backscatter (BUB) and integrated reflection coefficient (IRC) to predict density and mechanical properties of trabecular bone, as compared to normalized broadband US attenuation (nBUA) and speed of sound (SOS). These acoustic parameters were measured in 41 in vitro samples of bovine trabecular bone and correlated with a number of mechanical parameters and with volumetric bone mineral density (BMDvol). BUB correlated statistically significantly with the volumetric bone mineral density (r = 0.61, p < 0.01), Young's modulus (r = 0.40, p < 0.01) and ultimate strength (r = 0.40, p < 0.01). IRC was even more strongly correlated with BMD(vol) (r = 0.92, p < 0.01) and most of the mechanical parameters (0.81 < r < 0.85). Strong correlations were also found between mechanical parameters and SOS (0.87 < r < 0.90). No significant correlation was found between attenuation (nBUA) and either BMD(vol) or mechanical parameters. Reproducibilities (standardized CV%) of BUB (3.5%) and IRC (1.5%) were comparable to those of nBUA (2.3%) and SOS (0.5%). To conclude, BUB and IRC are promising parameters for the evaluation of density and mechanical properties of trabecular bone. Advantageously, BUB and IRC can be determined with a single transducer, hypothetically enabling measurements at many clinically relevant fracture sites.