Adaptive diagnostic ultrasonic imaging

Medical ultrasonic imaging systems assume a constant, fixed acoustic propag ation velocity in tissue. This assumption allows the focusing of ultrasonic pulses in a simple way with transducer arrays with electronic delay lines. However, soft tissue acoustic velocities actually range from 1350 m/s to 1 725 m/s, and the basic focusing procedure fails to obtain high quality imag es on some patients. Here we describe different adaptive techniques that al low focusing through such inhomogeneous tissues. (C) 2001 Academie des scie nces/Editions scientifiques et medicales Elsevier SAS.