Ultrasonic speckle reduction using nonlinear echo combinations

摘要

An ultrasonic imaging apparatus and method are described for imaging nonlinear response objects such as contrast agents and tissue with reduced speckle artifacts. A pulse sequence of two or more pulses of differing amplitude, polarity, and/or phase characteristics is transmitted in each beam direction and an ensemble of echoes is received for each sampled point in the image field. The echoes are combined by different nonlinear signal separation processes and these results are combined to reduce image speckle by a frequency compounding effect. Nonlinear separation techniques which can be used include pulse inversion, power modulation, and combined power modulation/pulse inversion.