Golay excitation for dual-frequency tissue harmonic imaging

Ultrasound tissue harmonic signal generally provides superior image quality as compared to the linear signal but with limited penetration and the sensitivity due to low signal-to-noise ratio (SNR). The method of third harmonic (3f0) transmit phasing can improve the tissue harmonic SNR by transmitting at both the fundamental and the 3f0 frequencies to provide mutual enhancement between the second harmonic components. To further increase the SNR without excessive transmit pressure, the phase-encoded Golay excitation can be incorporated in 3f0 transmit phasing to boost the tissue harmonic generation. The resultant frequency-sum and frequency-difference components of tissue harmonic signal can be simultaneously Golay-encoded for SNR improvement. Results indicate that the tissue harmonic SNR increases by about 11 dB without noticeable compression artifacts.