ASSESSMENT OF BONE-DENSITY USING ULTRASONIC BACKSCATTER

The goal of this project was to investigate the utility of ultrasonic backscatter for the assessment of bone status. Ultrasound offers a low -cost, portable, nonionizing alternative or complement to common X-ray - or radioisotope (gamma ray)-based methods of bone densitometry, Ultr asonic backscatter may provide useful information not revealed by ultr asonic attenuation and sound-speed densitometers, Backscatter is sensi tive to microstructural variations in acoustic impedance and should th erefore provide information regarding architecture (which is related t o fracture risk), as well as density. Ultrasonic backscatter at 2.25 M Hz and CT bone densitometric data have been acquired from 10 healthy h uman volunteers, The degree of correlation between CT and ultrasonic b ackscatter is high (r = 0.87, p < 0.001). The envelope signal-to-noise ratio was 1.81 +/- 0.08 (mean a standard deviation). This suggests th at the number of scatterers per resolution cell is large, the radiofre quency signal approximately obeys circular Gaussian statistics, and th e envelope obeys Rayleigh statistics. These results indicate promise f or ultrasonic backscatter as a substitute for or an adjunct to other u ltrasonic measurements (attenuation and sound speed) and X-ray measure ments for the assessment of bone status. (C) 1998 World Federation for Ultrasound in Medicine gr Biology.