Abstract: Elastography is an ultrasound imaging method, which visualizes the elastic properties of biological tissue which is often impossible with conventional ultrasound images. The tissue is hereby compressed. The local tissue strain can be visualized by comparing the ultrasound images acquired before and after compression, in order to differentiate between hard and soft tissue types. In this comparison, the time shifts of corresponding ultrasound echo signals are computed locally at one or more locations, which is time-consuming with conventional methods. The system for fast calculation of strain images from ultrasound echo signals described in this patent calculates iteratively the zero crossing of the phase of the complex HF-echo signals that are downshifted into the baseband.