Lesson 23 (Part 2)

Question 1

What factors affect magnitude in spectral doppler? (2)

Answer 1

1. Speed of blood flow
   - eg. within a stenosis
2. Doppler angle

Question 2

What is the magnitude within a stenosis?

Answer 2

Faster

Question 3

Doppler angle

Answer 3

Between the scan line and the blood flow

Question 4

What can doppler flow affect?

Answer 4

The calculated Doppler velocity

Question 5

What does a larger doppler angle mean? (2)

Answer 5

1. Smaller doppler shift
2. Slower velocity calculated
   - without angle correct

Question 6

What factors affect amplitude? (4)

Answer 6

1. Brightness
   - intensity of the returning echo
2. Concentration of the RBCs
3. Reflectors
4. Impedance

Question 7

What are the special controls for spectral doppler? (4)

Answer 7

1. Gate size/sample volume
2. Gain
3. Spectral invert
4. Baseline

Question 8

What does gate size/sample volume affect?

Answer 8

Range of resolution

Question 9

Range of resolution

Answer 9

Knowing exactly where the signal is coming from

Question 10

What is the opposite of range resolution?

Answer 10

Range ambiguity

Question 11

What does gain do in spectral doppler?

Answer 11

Amplifies the incoming echoes’ voltage

Question 12

Where are arteries normally compared to the baseline in spectral doppler?

Answer 12

Above the baseline

- positive signals

Question 13

Where are veins normally compared to the baseline in spectral doppler?

Answer 13

Below the baseline

- negative signals

Question 14

Can you move baseline?

Answer 14

Yes

Question 15

What does wall filters do in spectral doppler? (2)

Answer 15

1. Cuts off slower flows

2. Gets rid of clutter

Question 16

What is considered to cause clutter? (2)

Answer 16

1. Tissue motion

2. Valves

Question 17

What can PRF affect?

Answer 17

Scale

- which velocities we can display

Question 18

What happens if we decreases the PRF too much?

Answer 18

It will cause aliasing

- wrap around

Question 19

What happens if we increase the PRF too much?

Answer 19

It will produce a poor signal

- wasted space

Question 20

What does increasing the PRF try and show?

Answer 20

Faster flow speeds

Question 21

What happens to the doppler shift when ingle correction increases?

Answer 21

It decreases

Question 22

What is velocity calculated from?

Answer 22

From doppler shift

Question 23

What does correcting the angle do?

Answer 23

Brings the calculated speed back up to its true value

Question 24

What can spectral doppler be converted to?

Answer 24

An audible signal

Question 25

What do higher frequencies have?

Answer 25

Higher pitches

Question 26

What do lower frequencies have?

Answer 26

Lower pitches

Question 27

Wy can we hear spectral doppler?

Answer 27

Because they are in kHz

- this is in audible range

Question 28

What can audible signals do?

Answer 28

Be turned up or down

- volume

Question 29

What can we do at areas of higher volumes/speeds?

Answer 29

Listen

- we can hear them