Suppression of propagating second harmonic in non-linear imaging

Harmonic imaging can improve contrast between contrast agents and tissue when imaging microvasculature. However, the factor limiting contrast enhancement is harmonic signals generated by the medium as the ultrasound signal propagates through it. Here, the authors have developed a method known as the Harmonic Cancellation System (HCS) to suppress this propagating second harmonic and improve contrast between contrast agents and the surrounding tissue for harmonic imaging. Simulations and experiments have shown that the level of second harmonic signals can be reduced by about 30 dB using HCS.