Harmonic generation with a dual frequency pulse

Nonlinear imaging was utilized in commercial ultrasound systems over the last 15 years offering major advantages in many clinical applications. In this work, pulsing schemes (pulse inversion, power modulated pulse inversion and power modulation) coupled with a dual frequency pulse are presented and investigated for tissue harmonic imaging. The performance and limitations of the new method was evaluated with both acoustic pressure measurements and theoretical simulations, and was compared with those of a conventional single frequency pulse. It is shown that the proposed technique extracts harmonics both at the low and high end of the frequency spectrum thus offering improvements in penetration and resolution, respectively. Pulse inversion greatly benefits from dual frequency pulses as it now contains a large amount of nonlinear fundamental that was not present with single frequency pulses.