P3B-5 A Feasibility Study of Tissue Harmonic Generation with 3f0 Transmit Phasing

Tissue harmonic imaging suffers from low signal-to-noise ratio (SNR) under typical imaging conditions. On the contrary, presence of strong tissue harmonics also degrades microbubble detection in contrast harmonic imaging. Therefore, a novel approach for both enhancement and suppression of tissue harmonic signal is developed by phasing transmit signal at 3
f

₀
frequency. Results indicate that the relative phasing between the frequency-sum component and the frequency-difference component markedly changes the amplitude of the second harmonic signal over a wide range of axial depths. For harmonic enhancement, approximate 6 dB increase of second harmonic amplitude can be achieved with improved lateral harmonic beam pattern. For harmonic suppression, the second harmonic signal can be significantly reduced by about 11 dB. Hence, the method of 3
f

₀
transmit phasing has potentials both for improving SNR in tissue harmonic imaging and for enhancing image contrast in contrast agent imaging by suppression of tissue harmonic background.