Ultrasound parametric imaging of bone in vivo

The measurement of ultrasound frequency-dependent attenuation and velocity is a new technique of investigation of skeletal status. An ultrasound transmission scanning system was constructed to make in vivo parametric images of the acoustic properties of the heel. Images were obtained in transmit mode by using a pair of broadband focused transducers (center frequency 0.5 MHz, diameter 29 mm, focus 50 mm) immersed in a water bath at room temperature. The total duration of the acquisition period was 3 minutes. Comparison between the image of the slope of attenuation and the X-ray radiograph of the calcaneus was possible in one case. All the anatomical details could be identified on both images. The images reported here demonstrate the wide range of values of slope of attenuation found in the bone thus reinforcing the idea of tremendous heterogeneity of the acoustic properties of bone. This suggest that the accurate control of the position of the measurement site is of the utmost importance for between subject comparison and for repetitive measurements