[Biological tissue strain imaging with freehand elastography]

An imaging technique of deformation under load of a biological soft tissue, from numerical processing of radiofrequency ultrasound images is presented. The 2D locally regularized estimation method determines deformation parameters as the arguments that maximize a similarity criterion between a pre-compression region and its deformed version, compensated for according to these parameters. The technique was assessed with ultrasound data acquired during freehand scanning on two dedicated elastography phantoms as well as ex vivo bovine liver samples, containing artificial lesions made with agar gel. Although the load conditions are complex, elastograms are easy to interpret, exhibiting the inclusions with sharp boundaries.