Chapter 5 tutoring

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1

In a stenotic vessel explain what happens to velocity, pressure and volume.

velocity increases
pressure decreases
volume increases

2

Which reaction occurs at a stenosis?

A) a drop in pressure
B) a drop in velocity
C) a drop in volume

a drop in pressure

3

As the average speed rises the Reynolds #

A) decreases
B) increases
C) stays the same

B) increases

4

Reynolds # formula

(Velocity * Density * Diameter)/ Viscosity

5

As the diameter increases what happen to Reynolds #

Increases

A rise in viscosity is the only variable that will decrease R#

6

As the viscosity increases what happen to Reynolds #

decreases

A rise in viscosity is the only variable that will decrease R#

7

Doubling the radius of a vessel Decreases resistance to

1/16 of the original value

8

How many transducers does CW have?

2

9

Can CW determine depth?

NO

10

Which forms of ultrasound uses the Doppler effect?

cw, pulsed-wave, color-flow, color doppler energy (NOT STATIC) Doppler would be useless in

11

aliasing

12

range ambiguity (depth confusion)

13

Can distinguish movement in both directions

bidirectional

14

Small gate (sample volume)

Gives you High Signal: Low Noise

15

With PW Doppler, the pulser generates _____ cycles of pulses.

5-30

16

The longer the vessel/tube the ______ the resistance

higher

17

Flow at the beginning of the tube is likely to be ______

PLUG flow

18

Flow going in same direction is ______

Laminar flow

19

If you double pressure what happens to volume?

Pressure is directly proportionate to Volume (flow)

20

If length of tube increases, what will happen to Flow will?

w will decrease. Flow and Length are indirectly proportionate.

21

If you increase viscosity, what happens to velocity?

velocity decreases

22

The inertia of the blood and vessels causes pressure to _______ when the velocity of blood flow increases

decrease

23

Density formula

mass/volume

24

Pressure that is static flow

omnidirectional

25

Reynolds number has NO UNIT

...

26

Venous flow is non ______

pulsatile

with a wide range of velocities

27

Viscosity unit

Poise

28

Blood flows from _____ pressure to ____ pressure

high to low

29

Viscosity can be defined as

the measurement of a liquid's resistance to flow

30

Turbulent flow =

2000-2500

31

Receiver is moving away from the Source

shift decreases

32

Moving in opposite direction

the max neg – Doppler shift

33

Correction line (angle) must be aligned _____ to correct

parallel

34

Doppler shift formula

Doppler shift = 2V cos0 Fo/C

35

The Doppler shift frequencies at 90 degrees =

Zero

36

Increasing the ensemble length ________ the frame rate.

decreases

37

Increasing ensemble length improves color sensitivity and accuracy and decreases _______

frame rate

38

Color map baselines are always represented by ______.

black.(NO Doppler shift)

39

Steering the color window(gate, or box) to the right or left produces an _______ frame rate.

unchanged

40

Compared with Doppler-shift imaging, Doppler-power imaging is more ______.

sensitive

41

Color Doppler frame rates are ______ gray-scale rates

less than

42

Frame rate =

frames per second

43

An earlier gate time means a ________ sample volume depth.

shallower

44

Flow reversal in diastole indicates _____ distal resistance.

high

45

what is the significance of large ensemble length

more sensitivity - ability to detect low flow
increase accuracy
decreased temporal resolution

46

Decreasing the size of your color box has what effect on framerate

Increases frame rate

larger area reduces frame rate*

47

Increasing the size of B-mode area does what to frame rate

decreases Frame rate

48

Changing Doppler gain has what effect on framerate

Changing Doppler gain –has NO effect on frame rate

49

Nyquist limit

1/2 PRF

50

Which one has the slowest flow? looking at map

It will be the scale/map with the lowest #

51

What changes the colors in an image?

color map

52

If venous flow is on the top , and goes to bottom of baseline how would you get it back to normal(correct it)?

Invert

53

Changing sweep speed does not affect ____ or _____ It changes amount of waves displayed

height or width

answer was none of the above

54

CW duty factor

100% or 1

55

If all the blood in vessels in a color box (gate)were traveling same speed—Spectral broadening _____ occur

would not

56

20.

Spectral Doppler is still SPECTRAL Doppler even if edges are colored..(don’t be tricked)

57

The removal of unwanted noise /clutter

Wall filter

58

The process of transforming the returning Doppler signals is accomplished by what

FFT

59

The horizontal scale represents

Changes in velocity & Frequency

60

Power Doppler doesn’t report

Velocity

61

CW is used in _____ Doppler instruments

SOME

62

range ambiguity
measures high velocities
NO aliasing
does not make pictures.

63

How many pulses in color flow Doppler to write 1 line?

5 - 30 , 10 - 20 average

64

How do you turn on gate location?

turn on spectral

65

How many pulses in B-mode to write 1 line?

1-3 pulses

66

In Doppler shift blood flow moving away from the transducer will ______ the frequency of the sample wave

decrease

67

Opening the gate

68

Gate determines ____

depth (time and depth)

69

discriminate range

70

no aliasing

71

The range of velocity is controlled by

the scale

72

Y axis =

time

73

90 degree angle=

ZERO shift

74

As angle increases—

it miscalculates more

75

Cosine of 60 is---

.05

76

True or false

Cosine increases as angle decreases

True

77

If the cosine increases what happens to the Doppler shift?

Increases

78

What is the correct Doppler Shift equation?

FD = (2 * V* cos0 * f0)/c

79

Velocity calculation error increases as the cosine angle _____.

increases

80

True or False
In CW the angle doesn’t influence the Doppler shift

True

81

The ensemble length is the _______

Packet size

82

48.Primary colors are

red-yellow-blue

83

the 3 basic hue colors

Red-Blue-Green

84

freezing the grayscale like in m mode, _______ the frame rate

INCREASES the frame rate

85

51 no motion=no Doppler shift=black on color map

...