A novel quantitative ultrasound metric for osteoporosis diagnosis using instantaneous phase

Quantitative ultrasound (QUS) has emerged as a promising and cost-effective method for assessing bone health. Traditional QUS parameters such as broadband ultrasound attenuation and speed of sound are valuable; however, they are difficult to measure at central skeletal sites such as the hip and spine where most osteoporotic fractures occur. This study introduces a novel QUS method derived from the instantaneous phase of the backscattered ultrasound signal. Backscatter techniques use a single ultrasonic probe which allows access to more skeletal locations. By leveraging the unwrapped phase information extracted from the Hilbert transform, the slope of the phase accumulation was measured as a function of time. The slope correlated strongly (R > 0.9) with the density of specimens of human cancellous bone measured in vitro with a 3.5 MHz transducer. These results suggest that phase accumulation measurements obtained from the Hilbert transform of backscatter signals may detect osteoporotic changes in cancellous bone.