Broadband ultrasound scanning and frequency sweep measurement for trabecular bone with novel wideband single crystal transducer

Abstract

Quantitative ultrasound has been developed as a radiation-free technique to evaluate both bone density and strength. The ultrasound parameters, such as velocity (UV), attenuation (ATT), and broadband attenuation (nBUA), have been widely used as indicators for bone health status. In our study, a novel spiral-wrapped wideband ultrasound transducer is developed by TRS. Bovine trabecular bone samples (15 mm thickness) were prepared for frequency scanning. In each group, TRS transducer was used to emit the frequency from 0.5 to 7 MHz to propagate through samples; and pulses were received by the hydrophone. Frequency sweep response mostly correlated to bone density at frequency under 3 MHz, and barely showed any correlation with bone density at a frequency above 3 MHz, as higher frequency ultrasound energy attenuated significantly in trabecular bone. With controlled bone density reduction by 34.71%, UV decreased from 2575.03±34.38 m/s to 1717.15±48.19 m/s, ATT decreased from 3.66±0.71dB to 2.21±0.76 dB, and nBUA decreased from 2.09±0.96 dB/MHz/cm to 1.21±0.47 dB/MHz/cm. Generally, bone density decrease resulted in UV, ATT, and nBUA decreases, but were sensitive to the change of the wideband frequency from 0.5 MHz to 0.8 MHz. This new wideband transducer offers more information than the conventional ultrasound transducer, and can thus be used as a modality to evaluate bone health status.