What information does the ultrasound system calculate to display color flow?

Color flow Doppler imaging displays the mean Doppler frequency shift, which represents the average velocity of blood flow within a sample volume. The ultrasound system uses autocorrelation to process Doppler signals and compute the mean frequency shift. This provides a color-coded map of blood flow velocities, allowing for visualization of flow direction and speed. The mean Doppler frequency is displayed as different colors, with each color representing a range of velocities.