Propagation velocity and attenuation of a shear wave pulse measured by ultrasound detection in agarose and polyacrylamide gels.

The aim of our research was to measure and analyze phase velocity and pulse attenuation of a shear wave in two media: well-known agarose-gelatin gel and seldom-used polyacrylamide gel. These quantities were determined at three temperatures by the method of transmission sonoelastography described by Catheline et al. (1999). The shear wave was generated with a shaker stimulated by an electric pulse, with a length of one sinusoidal period with a preset frequency. The calculation method is based on a cross-correlation algorithm used for consecutive A-scans of signals of backwards scattered ultrasonic pulses. It allows determination of the local displacement of scattering elements in the medium, caused by a propagating shear wave, and determination of viscoelastic properties of gels. The results of the measurements of shear wave phase velocity and attenuation, obtained for agarose-gelatin and polyacrylamide gels that simulate biological systems depending on frequency and amplitude of vibrations, are presented. The comparison of the measured characteristic properties of gels has revealed that polyacrylamide gel is more useful in viscoelastic investigations of tissue-like phantoms.