Direct comparison of single mode versus fast and slow wave modes analyses of calcaneal bone data Free

Background: We previously demonstrated that a signal transmitted through cancellous bone might be comprised of two interfering (fast and slow wave) modes even though it appears to consist of only a single mode. Objective: The goal of this study was to compare the results of single mode analysis and two mode analysis to quantify the effects of interfering waves on the measured speed of sound (SOS) and broadband ultrasound attenuation (BUA). Methods: A series of human calcaneal samples (bone volume fractions = 0.09 to 0.21) were measured medial-laterally using 500kHz broadband focused transducers. Phase velocity was determined by phase spectroscopy and attenuation was determined by log-spectral subtraction. The original radiofrequency signal and the Bayesian-separated fast and slow wave radiofrequency signals were analyzed. Results: For each of the specimens, the slope of attenuation determined by single mode analysis was larger than that for either the fast or slow wave, and the speed of sound determined by single mode analysis lay between that of the fast and slow wave. Conclusion: The additional information provided by analyzing individually fast and slow wave modes might enhance the effectiveness of bone sonometry. Supported by NIH/NIAMS grants R01AR057433 and P30AR057235.