On the accuracy of coherent compounding Doppler imaging

The influence of blood motion on the accuracy of coherent compounding Doppler imaging is investigated. A simplified model for the compounded Doppler signal is proposed. The model is used to show that coherent compounding acts as a low pass filter, inferring a negative shift of the Doppler spectrum and a bias in mean frequency estimates. Simulations and in vitro experiments were used to quantify the bias and signal-to-noise ratio (SNR) for different velocities and beam-to-flow angles. Further, a multi-angle vector Doppler approach is proposed for 2D correction of blood motion during coherent compounding, which was verified in simulations and in vitro to improve SNR and substantially reduce the mean velocity bias.