Acceleration effects in doppler ultrasound signals from - pulsatile flow

Conventional methods for estimating the Doppler spectrum apply the Fast Fourier Transform to data segments over which the signal is considered stationary. In the accelerative and deccelerative phases of systole this assumption is often unreasonable and a better understanding of the effect of nonstationarity on the Doppler spectrum is needed. Simulated signals were used to study the influence of blood acceleration on the Doppler spectral width for several sample volume sizes and data segment duration. For short duration data segments acceleration has almost no effect on the spectral width, but the spectral estimate has a low resolution, for longer windows the resolution is much better but in the presence of acceleration the Doppler spectrum is much broader.