Real-time pulse compression in multigate spectral Doppler imaging

The quality of Doppler ultrasound blood flow investigations is often affected by a low signal-to-noise ratio due to the weak energy backscattered by erythrocytes flowing in deep vessels. Transmission of coded pulses and matched receive filtering improve the penetration depth while preserving the axial resolution. However, the involved additional computational load has probably so far discouraged the massive implementation of pulse compression methods in real-time Doppler imaging systems. In this paper, we report on the performance obtained by the pulse compression technique applied to (multigate) spectral Doppler imaging. A real-time algorithm was implemented on the ULA-OP research scanner. The results of phantom experiments show that up to 13dB signal-to-noise ratio gain can be obtained when a 5 μs-long linear chirp is transmitted. Furthermore, in-vivo tests demonstrate that pulse compression is an effective means to increase the penetration depth, by up to 2 cm, in spectral Doppler applications.