If no color appear in the vessels in color Doppler
The angle between direction of flow and the sound beam is 90
What will make color appear in a vessel with color Doppler
An angle other than 90 must be created between the direction of flow and the direction of the sound beam
Will color ever appear if the sound and flow are perpendicular?
No
Color confetti
Color gain set inappropriately high and color appears throughout the color box
What single control on an ultrasound system can make color disappear?
Color gain set too low
When does grey scale noise appear in spectral Doppler gain
When the Doppler gain is set too high
What happens when you turn the gain too low
Not only does the noise vanish, so does the meaningful Doppler spectrum
Can color Doppler have aliasing
Yes
How can you tell bidirectional flow in color Doppler?
Flow reversal is present in a vessel when the colors red, black, and blue are next to each other
How can you tell aliasing is present in color Doppler?
When the top color from the color map touches the bottom color
How to tell aliasing from bidirectional flow
If the colors that touch each other in the image go through the maps middle it's flow reversal. If the colors that touch go around the outside of the map aliasing is present
How can you reduce/eliminate aliasing on color Doppler?
Increase the velocity scale
Can you use CW Doppler to eliminate aliasing in color Doppler?
No, this is not an option
How does increasing the scale effect color Doppler images negatively?
It decreases the sensitivity to slow flows and some low velocities can be lost
What do wall fillers eliminate?
Selectively eliminates low frequency Doppler shifts
Do wall fillers affect high velocities?
No, it leaves all high velocities unchanged
What types of Doppler can you use wall filler?
Color flow and spectral Doppler
What does wall filler do on spectral ultrasound?
Eliminates low frequency Doppler shifts near the baseline