Topics and Color Flow Direction

Question 1

What is rouleaux flow?

Answer 1

RBC’s stack up in a column.

Question 2

Why is rouleaux flow seen in an ultrasound image?

Answer 2

It forms a larger reflector so they can be seen easily in B-mode. It is sludge like in B-mode.

Question 3

What is a B-flow control?

Answer 3

It is a control on some ultrasound machines that allow you to see flow while not using doppler.

ie. no angles.

Question 4

What is a flash artifact?

Answer 4

If you move the probe over the skin, you get a lot of color flashing across the skin.

Question 5

When does flash artifacts ocurr?

Answer 5

It occurs more readily with low scale and high gain.

Question 6

How should you avoid flash artifact?

Answer 6

Best to move slowly in order to avoid it.

Question 7

What control has more flash artifact than velocity color?

Answer 7

Power control.

Question 8

What is the power doppler/color?

Answer 8

Display of the frequency shifted amplitudes (or power)

Question 9

In power doppler, what isnt displayed?

Answer 9

Velocity and direction.

Question 10

Power doppler is less affected by what?

Answer 10

angles.

Question 11

Does aliasing occur with power doppler?

Answer 11

no, because there is no velocity display.

Question 12

What is power doppler good for?

Answer 12

It is a good way to show course of branches.

Question 13

Why is the color variance map different from a typical velocity color map?

Answer 13

Because it displays the amount of turbulence in the flow.

Question 14

What does the color variance map do?

Answer 14

It basically shows laminar vs turbulent areas of slow in a vessel by a color change side to side on a velocity color bar.

Question 15

What is turbulence?

Answer 15

A big range of velocities.

Question 16

What does a regular color map show?

Answer 16

It shows the the mean of that range.

Question 17

In a color variance map image, what does red mean?

Answer 17

It means velocity toward beam.

Question 18

In a color variance map image, what does blue?

Answer 18

It means velocity is away from the beam.

Question 19

In a color variance map image, what does yellow mean?

Answer 19

Yellow is huge range of velocities towards the beam.

Question 20

In a color variance map image, what does aqua mean?

Answer 20

Aqua is a huge range of velocities away.

Question 21

The color variance map is different from a typical velocity color map because it displays which of the following?

a. Peak frequency shifts
b. Mean velocities only
c. Range of frequency shifts.
d. Amplitude of frequency shifts.

Answer 21

c. Range of frequency shifts.

Question 22

What kind of angle does flow toward the beam yield?

Answer 22

an acute angel.

Question 23

What kind of angel does flow away from the beam yield?

Answer 23

An obtuse angel.

Question 24

What two colors on the image that have black between them show?

Answer 24

It shows two different directions of flow relative to the beam.

Question 25

what does the two colors on the image that wrap around from the highest color (aqua) to the lowest color (yellow) represent?

Answer 25

Aliasing.

Question 26

Why does the aliasing artifact occur?

Answer 26

• The peak frequency shifts (peak velocities) are less than 2 times the PRF (Nyquist limit).
• basically, the f shifts are too high for the equipment settings.

Question 27

What are the equipment reasons for aliasing?

Answer 27

• scale too low.
• baseline too high.
• probe frequency too high.

Question 28

What are the physiologic reasons for high F shift?

Answer 28

• Stenosis
• AVF
• High flow rate
• Narrowing branch or vessel.

Question 29

Curvilinear or sector probes have a doppler beam lines that _______?

Answer 29

Fan out.

Question 30

What is a frozen color image?

Answer 30

It is temporal.

a snapshot in time.

Question 31

Is color diagnostic?

Answer 31

NO

Question 32

What does color document?

Answer 32

It documents a moment in time in one slice of a vessel.

Question 33

How must you confirm a color image?

Answer 33

With doppler information.

Question 34

What is the difference between doppler waves and a frozen color image?

Answer 34

Doppler waves: gives velocity and direction information over a period of time.

Frozen color image: just a moment in time.