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SPI > Doppler Pt 2 > Flashcards

Doppler Pt 2 Flashcards

1
Q

when color obscures the gray scale display of soft plaque because resolution of color doppler is lower than gray scale

A

blooming artifact occurs

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2
Q

clutter is reduced by

A

increasing PRF or wall filter or reducing color gain

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3
Q

___ persistence levels should be used to optimize color doppler of cardiac structures

A

low

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4
Q

___ persistence levels should be used for slow flow in levels

A

higher

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5
Q

best way to optimize color

A

use a smaller color box for higher frame rate–fewer scan lines needed

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6
Q

smaller samples = less data to collect and process =

A

faster frame rate

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7
Q

decreased color gain is not related to

A

flash artifact

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8
Q

decreased color scale and filter and increased color priority are related to

A

flash artifact

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9
Q

primary CW advantage

A

no Nyquist limit

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10
Q

frequency and peak doppler shift relationship

A

direct

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11
Q

resistance and velocity increase at

A

arterial stenosis

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12
Q

PQ at PRF of 5000/s, max doppler frequency that can be detected =

A

2.5 kHz

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13
Q

Nyquist limit =

A

PRF / 2

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14
Q

increased threshold/priority will display

A

more color flow (more low velocity flow)

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15
Q

decreasing scale and filter settings will allow for display of

A

lower velocity flow

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16
Q

increasing gain will

A

amplify doppler shifts detected and increase color flow

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17
Q

if reflector and sound source are moving at the same speed and direction

A

doppler shift will not be detected

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18
Q

if stenosis/blockage reduces lumen to 1/2 normal area, velocity of flow at stenosis must ____ to maintain flow rate

A

double

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19
Q

Primary PW advantage

A

range resolution

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20
Q

In PW, how often blood flow is sampled is determined by

A

PRF

as PRF increases, pulses are emitted at a faster rate which leads to faster sampling

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21
Q

assesses data from multiple sampling sites and produces a display representing mean flow velocities–color

A

autocorrelation

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22
Q

used to process PW

A

FFT

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23
Q

used to assess and describe pressure gradients in blood flow

A

Bernoulli equation

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24
Q

doppler shift exceeding ____ causes aliasing

A

Nyquist limit

25
Q

velocity and doppler shift relationship

A

direct

26
Q

sample size and frame rate relationship

A

inverse

27
Q

____ to change course of the vessel across image and allow vessel to accurately display a single color

A

heel to toe

28
Q

to demonstrate more cardiac cycles on PW

A

decrease sweep speed

29
Q

has 2 separate elements so is not limited to pulse echo parameters like PRF and Nyquist

A

CW

30
Q

changing color flow doppler velocity scale alters

A

PRF

31
Q

increasing transmit frequency increases risk of

A

aliasing

32
Q

power doppler disadvantages

A

slow frame rates and flash artifact

33
Q

refers to how long color is displayed on screen for each doppler shift, produces smoother image

A

persistence

34
Q

____ persistence will ____ the amount of time a color pixel is displayed over an area

A

increasing

increase

35
Q

low persistence should be used for

A

fetal cardiac assessment

36
Q

cross talk

A

type of mirror image artifact

37
Q

of pulses per scan line increases, color packet size ___, frame rate ___

A

increase

decreases

38
Q

increased when evaluating venous flow

A

color priority

39
Q

used in bidirectional doppler systems

A

quadrate phase detection

40
Q

element ___ has no effect on doppler shift

A

width

41
Q

element ___ determines doppler frequency

A

thickness

42
Q

(2 x blood velocity x transducer frequency x cos (angle)) / speed of sound in ST =

A

doppler shift

43
Q

as velocity increases pressure

A

drops

44
Q

most common doppler artifact

A

aliasing

45
Q

to best display arrhythmia

A

reduce sweep speed

46
Q

refers to # of pulses / scan line used for doppler imaging

A

ensemble length

47
Q

color doppler has ___ temporal res

A

worst

48
Q

M-mode has ___ temporal res

A

best

49
Q

cos and calculated velocity relationship

A

inversely proportional

50
Q

peak velocity of 60 cm/s is obtained at 0 degrees, at 60 degrees the actual velocity is

A

120 cm/s

51
Q

increasing PRF will reduce ___ while increasing ___

A

aliasing

appearance of range ambiguity

52
Q

increased wall filter will

A

reduce low level echoes

53
Q

____ can be used to increase # of scan lines in color

A

persistence

54
Q

increased frequency will reduce ____ and increase ____

A

range ambiguity

aliasing

55
Q

blood flow that varies with respiration

A

phasic

56
Q

5 MHz CW and 5 MHz PW are fired at the same time, which will produce spectral wave first?

A

they will produce spectral wave at the same time

speed of sound in the body is the same for both transmitted waves

57
Q

increased hematocrit = increase viscosity = thicker blood =

A

decreased flow velocities

58
Q

decreased hematocrit = decreased viscosity = thinner blood =

A

increased flow velocities

59
Q

avoid aliasing by

A 
reducing imaging depth
increase PRF (by increasing doppler velocity scale)
decrease transmit frequency
increase doppler incidence angle
shift 0 baseline
use CW doppler

SPI (3 decks)

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