Cancellous bone characterization using ultrasonic backscatter parametric imaging

Abstract

The ultrasonic imaging of the highly attenuated porous media (like spongy bone) is of great interest to the researchers. In this study, we used a 7.5 MHz focal transducer (V321, Panametrics, USA) to scan a total of 35 bovine cancellous bone samples. The −-6dB lateral resolution of the transducer was 0.157 mm which is comparable to the trabecular bone thickness (0.1–0.2mm). Apparent integrated backscatter (AIB) was calculated using different signal of interest (SOI) to reconstruct the ultrasonic backscatter parametric images. The trabecular bone structure can be clearly seen from the images. AIB was positively correlated with bone mineral density (BMD) (R = 0.61, p<0.05), bone volume fraction (BV/TV) (R = 0.53, p<0.05), and apparent bone density (ABD) (R = 0.58, p<0.05) when SOI was chosen around the surface of the bone sample, but negatively correlated with BMD (R=-0.77, p<0.05), BV/TV (R=-0.81, p<0.05), and ABD (R=-0.82, p<0.05) when SOI was chosen below the surface of the bone sample. We suppose that single scattering (SS) and multiple scattering (MS) may lead to this opposite correlation phenomena. When wavelength is comparable to the scatterer diameter, diffractive scattering is complex as predicted by Faran cylinder model. We suggest that MS may play an important role in cancellous bone characterization.The ultrasonic imaging of the highly attenuated porous media (like spongy bone) is of great interest to the researchers. In this study, we used a 7.5 MHz focal transducer (V321, Panametrics, USA) to scan a total of 35 bovine cancellous bone samples. The −-6dB lateral resolution of the transducer was 0.157 mm which is comparable to the trabecular bone thickness (0.1–0.2mm). Apparent integrated backscatter (AIB) was calculated using different signal of interest (SOI) to reconstruct the ultrasonic backscatter parametric images. The trabecular bone structure can be clearly seen from the images. AIB was positively correlated with bone mineral density (BMD) (R = 0.61, p<0.05), bone volume fraction (BV/TV) (R = 0.53, p<0.05), and apparent bone density (ABD) (R = 0.58, p<0.05) when SOI was chosen around the surface of the bone sample, but negatively correlated with BMD (R=-0.77, p<0.05), BV/TV (R=-0.81, p<0.05), and ABD (R=-0.82, p<0.05) when SOI was chosen below the surface of the bone sample. We suppose that si...