If the color map has a velocity scale of 17 cm/s and flow is at zero degrees to the sound beam, the colors at the ends of the bar would indicate which velocity relationship?

• A. Peak velocity of 17 cm/sec
• B. Average velocity of 17 cm/sec
• C. Peak velocity of 34 cm/sec
• D. Peak velocity above 17 cm/sec

Answer: (B)

Color Doppler velocity encoding uses a scale to map speeds to colors. When flow is aligned with the sound beam (angle is zero), the Doppler shift directly reflects the true velocity, so the colors on the map correspond to the actual speeds present in the vessel. The ends of the velocity bar represent the maximum speeds that can be displayed on that map. With a scale of 17 cm/s, the end colors indicate speeds at the scale’s limit in either direction, i.e., the peak velocity is 17 cm/s. The end colors do not signify an average velocity across the cross-section or speeds beyond the scale; they show the maximum speeds the map can depict.