Unit 11: Abnormal Carotid Color Flashcards
What is the “color” rule?
Never depend on color alone to distinguish carotid pathology.
Must be backed up with PW doppler.
When does color aliasing occur?
Velocities too high for scale.
What can cause color aliasing?
- Stenosis
- Low angle
- Scale low (PRF)
- Tortuosity (High velocity and lower angle)
What is the best demonstration of a stenosis in color?
Normal color proximally, then mosaic at narrowinfg.
What is a bruit?
It is a vibration of tissue at point of turbulence.
When is a color bruit shown?
It is shown when color pulses out into tissues.
What does a color bruit indicate?
It indicates a stenosis >50% but does not occur with every stenosis >50%
How do you create an interpretable color image of a stenosis with a color bruit?
- Take one image demonstrating the bruit
- To show the area of stenosis: take an image during diastole when the vibrations are less likely to be present.
- Use color gain carefully to avoid bleeding over plaque during diastole.
Why is rasing the scale benefical?
It may eliminate aliasing mosaic despite stenosis. It is helpful to see aliasing in at least one image of signifcant stenosis.
What is trickle flow?
FLow so low that it is like a trickle out of the faucet.
Nearly but not quite occluded.
How do you find trickle flow in a suspected occlusion?
- Decrease scale.
- Increase gain
- Decrease color box size.
- Look for flow in and beyond the bulb.
- Look in long and transverse views.
- Must investigate any areas of suspicion with PW or open SV and demonstrate no flow if there is none.
To best demonstrate significant stenosis in color, you must show:
- Normal color pre-stenosis
- Color aliasing at stenosis
- Color aliasing post-stenosis with turbulence.
Why should you use the power color?
To establish the course of the vessel.
What is an example of a color artifact?
Mirror image.
Where is a mirror image usually seen?
Often seen at the SCA.
