Vascular (doppler)

Question 1

Which parameter would profoundly affect the doppler equation?

Answer 1

-velocity of blood flow

Question 2

Types of Doppler

Answer 2

• CW
• spectral (duplex)
• spectral and colour (triplex)
• power

Question 3

What should angle correct be at?

Answer 3

60 degrees

Question 4

What can we do to improve our doppler angle?

Answer 4

• heel/toe
• angle correct (60 degrees)
• change colour box angle
• change window of insonation

Question 5

Where should the spectral baseline be positioned?

Answer 5

-1/3 from the bottom of spectrum (so we do not cut off diastolic flow)

Question 6

What is the direction of flow that is above the baseline?

Answer 6

-toward transducer

Question 7

What will a lg sample volume depict?

Answer 7

• unclean signal

- lots of velocities

Question 8

What will a sm sample volume depict?

Answer 8

-clean signal

Question 9

How does angle correct affect the signal?

Answer 9

Consistency Within:

• entire exam
• recheck exams
• patient to patient

Question 10

How much of the display should the spectral trace show?

Answer 10

-2/3rds

Question 11

What adjusts the scale?

Answer 11

PRF

Question 12

What happens if spectral wall filter is too low?

Answer 12

-wall thump from arterial systole

Question 13

What happens if spectral wall filter is too high?

Answer 13

-eliminates echoes within waveform

Question 14

What causes aliasing?

Answer 14

• PRF too low

- increase the velocity scale

Question 15

Where should the colour bar be set at for colour map? What will happen if you raise or lower the bar?

Answer 15

• in the middle

- inadequate colour representation

Question 16

What happens if the colour baseline is too low?

Answer 16

-only higher velocity flow will be shown

Question 17

What happens if the colour baseline is too high?

Answer 17

-only lower velocity flow will be shown

Question 18

What does red flow indicate?

Answer 18

-flow toward transducer

Question 19

What does blue flow indicate?

Answer 19

-flow away from transducer

Question 20

What happens if your colour box is too big?

Answer 20

• decreased frame rate

- poor resolution of colour

Question 21

What happens if your colour box is reduced to the vessel?

Answer 21

• increased frame rate

- improved image quality

Question 22

How should you steer the colour box?

Answer 22

-parallel to flow (0 or 180 degrees)

Question 23

What may you have to do with the colour box at a bifurcation?

Answer 23

-angle the colour box twice to show each branch (vessels are usually not parallel at bif)

Question 24

What will happen if a venous setting is used to visualize arterial flow?

Answer 24

-aliasing

Question 25

What happens if colour gain is set too low?

Answer 25

-no flow

Question 26

what happens if colour gain is set too high?

Answer 26

• flaring

- bleeding outside vessel (false echoes)

Question 27

Advantages of Power Doppler

Answer 27

• no aliasing
• angle independant
• increased sensitivity (detects low flows)
• useful for tortuous vessels
• increased accuracy for grading a stenosis

Question 28

Disadvantages of Power Doppler

Answer 28

• no velocity
• no direction
• poor temporal resolution (because it is so sensitive)