PW and CW Doppler provide peak velocity estimates, while CFI produces relative mean velocity estimates.

The numbers you see near the ends of a color bar represent the mean Nyquist limit (the maximum measurable mean velocity) color flow imaging can measure, not peak velocity estimates.

To obtain peak blood flow velocity estimates, you must use PW or CW Doppler. However, since color flow imaging very quickly identifies jet locations and spatial orientation, color makes it easy to see the area of highest velocity in any jet. You can then quickly position the Doppler beam in the area of highest velocity.

Color flow imaging eliminates the need for the meticulous and time-consuming “blind” searching necessary to assess the stream using Doppler alone.

Blood Flow Velocity: Concept Applied

How does all the color and velocity information apply during the sonographic examination? Examine the images for velocity information

Diastolic mitral inflow jet appears as dark red at the edges. The central higher velocity displays as light orange

The systolic blood flow moving away from the transducer is colored dark blue at the edges and progresses to light blue toward the center of the jet. However, at the center of the jet, the blood flow has a yellow and orange color but the flow has not suddenly changed direction, as yellow and orange indicate. This abrupt change in color is an example of color reversal due to aliasing.