Backscatter coefficient imaging using a clinical scanner.

A clinical ultrasound scanner has been integrated with a digital data acquisition system to record echo signals for off-line processing of quantitative acoustic backscatter images. The method used to determine backscatter coefficients accounts for experimental factors related to the beam directivity function, the transmitting and receiving electronics, and the attenuation path of the beam. After characterization and calibration of the ultrasound scanner according to the data processing requirements, the quantitative backscatter coefficient for tissue-mimicking phantoms are within 14% of a value predicted by scattering theory. On five normal volunteers, preliminary in vivo liver images of the acoustic backscatter coefficient are obtained. Results from this study are compared to previously published in vitro results.