Suppression of propagating second harmonic in ultrasound contrastimaging

摘要

Contrast agents, such as bubbles, are used in ultrasound tonenhance backscatter from blood. To increase contrast between thesenagents and tissue, nonlinear methods such as harmonic imaging can benused. Contrast is limited, however, by tissue second harmonic signals.nWe show that a major source of this signal is nonlinear propagationnthrough tissue. In addition, we present methods to suppress this secondnharmonic generation. One simple approach is to decrease the fumber ofnthe imaging system. Simulations show that doubling the size of thenarray, while keeping total power output constant, decreases propagatingnsecond harmonic generation. A second approach uses active noisencancellation to suppress second harmonic generation. A specific method,nthe harmonic cancellation system (HCS), is developed and presented as annexample. In simulations, HCS decreased second harmonic generation bynover 30 dB. Using such methods, contrast can be improved between tissuenand bubbles in harmonic imaging