Development of quantitative ultrasound to determine the physical properties of bone

The objective of this research is to develop new ultrasonic techniques to better estimate bone's physical properties and provide diagnostic means for the early prediction of osteoporosis. The work consists of four parts. First, frequency scanning method was proposed as a simple, precise means for the measurement of broadband ultrasound attenuation (BUA). This study compared the frequency scanning method with the widely used broadband pulse method and demonstrated that the BUA derived from the new technique was more reliable and precise. The new method generated higher correlation of BUA to bone properties than the broadband pulse technique. Most significantly, the frequency scanning method has turned some once insignificant correlations between BUA and bone properties into significant ones, such as the increase of the absolute r-value of the correlation between BUA in the longitudinal direction and BMD (from 0.25 to 0.62) and the correlation between medial-lateral BUA and the medial-lateral stiffness (from 0.31 to 0.55).; Second, a stratified model was proposed to investigate the ultrasonic wave propagation in the trabecular structure. The results have demonstrated that ultrasound velocity in trabecular bone was highly correlated with the bone apparent density (r = 0.97).; Third, statistic study was performed on the relationship between ultrasound properties and bone properties. Data showed that ultrasound velocity was mainly correlated to bone density (r ≥ 0.78) and bone stiffness (r ≥ 0.68).; The study also showed that ultrasound velocity was superior to the ultrasound attenuation and BUA in the estimation of the trabecular stiffness. The average percent of stiffness information predicted by ultrasound velocity was 54% for the pulse velocity and 48% for the tone burst velocity, which were much greater than the 10% for the ultrasound attenuation coefficient and 26% for the BUA.; Finally, a novel technique of acoustic scanning was introduced. The partial demineralization of bone specimens demonstrated that the acoustic scanning technique had the ability to detect the local ultrasound parameters and thus the local properties of bone.; In summary, ultrasound is a promising physical modality in the estimation of bone's properties. The acoustic scanning technique has enabled the ultrasound to detect the changes of bone's local properties and therefore provided the potential means of early prediction of osteoporosis. (Abstract shortened by UMI.)...