Colour aliasing: change the scale first

Question 1What does red mean on a colour Doppler image?

1. aTurbulence
2. bOxygenated blood
3. cArterial blood
4. dFlow in one direction relative to the probe, depending on the colour map chosen

Question 2A normal vessel flickers red and blue along its whole length. What do you check first?

1. aWhether every segment is narrowed
2. bWhether the colour scale is set too low
3. cWhether the patient has a fracture
4. dWhether the B-mode gain is zero

Question 3What suggests a true fast jet?

1. aNo colour with the beam at 90 degrees
2. bColour outside every vessel wall at maximum gain
3. cSmooth colour after raising the scale
4. dAliasing which stays at one narrowing after sensible adjustment

Question 4Why turn the colour gain down when colour spills outside the vessel?

1. aToo much gain paints colour beyond the real lumen
2. bIt raises the scale directly
3. cIt measures the pressure in the vessel
4. dIt changes the direction of the blood

Question 5Can colour aliasing alone grade a stenosis?

1. aNo. Use the anatomy, spectral Doppler and the relevant protocol
2. bYes, if the colour is blue
3. cYes, every mosaic is a severe stenosis
4. dNo, because colour Doppler never shows flow