System for rapidly calculating expansion images from high-frequency ultrasonic echo signals

• Main Authors: Pesavento, Andreas, Ermert, Helmut
• Format: Patent
• Language: English
• Published: 18.02.2003

The mechanical properties of biological tissue (e.g. parameters of elasticity) are of high interest for the characterization of the state of the tissue. In medical diagnostic, changes in the elastic properties reveal histological and possibly also pathological changes of tissue. Commonly known are the development of palpable swellings and lumps. In agriculture mechanical tissue properties are also of interest for the evaluation of the quality of meat. 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. In this way, time shifts of corresponding echo signals can be computed quickly and accurately, so that values of the tissue strain can be determined, for example, in real time and displayed in parallel with the conventional ultrasound B-mode image.