Transmitting frequency-modulated signal to increase signal-to-noise ratio of medical ultrasound image

To increase signal-to-noise ratio (SNR) of medical ultrasound image, a frequency-modulated (FM) ultrasound transmitted imaging method is developed, where a weighted linear FM ultrasound is transmitted to enhance the emission energy without increasing the emission ultrasound pressure, and the image signal is formed by the demodulated ultrasound. Employing the impulse response model of ultrasound transducer and the modulating-demodulating principle of FM signal, the simulation for ultrasound imaging is carried out. The simulation results show that the SNR of the image formed with FM signal transmitting gets 10 dB higher than that formed with traditional pulse transmitting. By the aid of the self-designed FM signal transmitting ultra-sound imaging experiment system, the B-mode ultrasound images of phantom are gained. The re-suits reveal that the SNR is enhanced by 5-8 dB with the proposed method, which performs better with the increasing imaging depth.