Reflection of backscattered fast and slow waves on bone porosity using 2D simulation

Based on analysis of attenuation and velocity of ultrasound wave, the bone quality can be estimated. Despite that, the bone quality assessment of quantitative ultrasound still not match with X-ray based densitometry measurement. Taking account fast and slow wave parameter is believed to improve bone quality assessment using ultrasound. However, the current technique successfully measured fast and slow wave is through transmission, which is limited to the certain part of the skeletal site. Based on simulation studies recently, pulse echo measurement technique is proposed to solve the problem by investigating the correlation between fast and slow wave observed from backscattered waves with bone porosity. The 2D simulation is conducted toward 18 bone models with 9 models with parallel orientation and 9 models with perpendicular orientation. By calculating the difference between the simulated waveforms obtained using the two bone models, the backscattered waves with various depths can be isolated from overall reflected waves. Fast and slow wave will be identified in time domain from 4 difference depth of backscattered waves obtained. At the depth of 2.5 mm to 3.5 mm of backscattered wave, two waves which are might be fast and slow waves can be observed in the time domain of the parallel orientation model at the time between 13 μs to 16 μs compared to the perpendicular orientation model. The correlation between fast wave amplitude with porosity shows a clear negative correlation (R² = 0.77) compared to slow wave amplitude. The results also have a good agreement with previous research. Using 2D simulation, the backscattered wave can be isolated and a fast and slow wave was successfully observed in time domain. Hence, focusing on fast wave parameter for pulse echoes measurement might provide an improvement in bone quality assessments.