Lecture 22

Question 1

Signal processor detects

Answer 1

Direction
Mean
Variance
Power

Question 2

Direction is based on

Answer 2

positive or negaative doppler shift

Question 3

The average velocity of blood in an area is _______ and ________

Answer 3

Calculated and displayed

Question 4

Variance is

Answer 4

The variety within the blood flow

Standard deviation

Question 5

Power is

Answer 5

Strength or intensity of the echo

Related to amplitude

Question 6

Power depends on

Answer 6

Reflectors- specular reflection vs. Scattering

Impedance- higher impedance mismatch = more reflection

Concentration of RBC’s - higher concentraion = more reflection

Question 7

Autocorrelation is

Answer 7

Math technique for colour doppler

Done with signal processor
Determines mean and variance

Question 8

Autocorrelation the are range of what pulses sent out per line and what is it usually

Answer 8

3-32

10-20

Question 9

Ensemble length is

Answer 9

pulse/ scan line

Question 10

More pulses are for

Answer 10

Accuracy of speed calculation

Sensitivity (picking out weaker echoes/ shifts - slow flow)

Question 11

Once the instrument processes the doppler dat it goes to ____

Answer 11

Display

Question 12

The display uses

Answer 12

Hue, staturation and luminance parameters

Question 13

Hue

Answer 13

What colour is shown

Question 14

Sturation is

Answer 14

The amount of colour

Question 15

Luminance is

Answer 15

Echo intenstiy and power/ brightness

Similar to 2D echo intensity
Stronger echoes - brighter

Question 16

Colour box/window

Answer 16

Can change the size - changes the coverage

Affects frame rate/ temp resolution

Question 17

Colour map shows slower speeds at ______ and faster at ____________

Answer 17

Middle of dial

Top and bottom of dial

Question 18

Colour map helps to interpret (3)

Answer 18

Mean velocities
Direction of flow/ sign
Variance - change in colour left to right

Question 19

____ - _____ spectrum most commonly used

Answer 19

Red - blue

Question 20

Red =

Answer 20

Positive shift (usually)

Question 21

Blue=

Answer 21

Negative shift

Question 22

Invert

Answer 22

Flips the colour map
Does NOT change the direction of flow
Simply adjust the representation

The carotid bifurcation above shows blood flow away from the transducer
We like arteries to be red
We can flip the colour map

Question 23

Baseline is

Answer 23

Zero point (no doppler shift)

Can move the baseline up or down based on what you want to fit on your map

Eg. All my flow is positive, dont need as much blue

Question 24

Cant control __________ in doppler

Answer 24

PRF

Not in 2D

Question 25

Changing our PRF (kHz), we change our _________

Answer 25

Scale (cm/s)

Question 26

We can pick up faster or slower ______ by increasing or decreasing PRF

Answer 26

speeds

Question 27

Decreased PRF = ________ scale

Answer 27

Decreased

Question 28

What happens if your scale is too high

Answer 28

Slower flows go undetected

Question 29

What happens if your scale is too low?

Answer 29

Faster flows alias

Question 30

Aliasing shows

Answer 30

Wrap around colour