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Sonographic Topics > Chapter 4: Doppler Imaging Artifacts > Flashcards

Chapter 4: Doppler Imaging Artifacts Flashcards

1
Q

the study of blood flow through the blood vessels of the body

A

hemodynamics

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2
Q

difference in fluid energy

A

energy gradient

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3
Q

No energy gradient =

A

no flow

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4
Q

the driving force of the blood through the blood vessels

A

pressure energy

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5
Q

Potential energy converts into _______

A

kinetic energy

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6
Q

gravitational potentional energy

A

hydrostatic pressure

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7
Q

describes relationship between gravity, the density of blood, and the distance between an arbitrary reference point (usually the heart)

A

hydrostatic pressure

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8
Q

form of energy loss; produced when kinetic energy is converted to heat as a result of friction

A

viscous energy

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9
Q

an object at rest stays at rest, and an object in motion stays in motion unless acted on by an outside first

A

inertia

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10
Q

total energy in a system never changes; there must be the same total energy at the end of a vessel as at the beginning; types of energy may be different between two points

A

the law of conservation of energy

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11
Q

kinetic energy + heat energy =

A

potential energy that was initially found at beginning of vessel

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12
Q

the volume of blood moving through a vessel per unit time

A

flow

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13
Q

The amount of f low in a blood vessel is ______ proportional to pressure gradient.

A

directly

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14
Q

systemic circulation

A

left ventricle of heart
aorta
arteries
arterioles
capillaries
venules
veins
IVC
right atrium of heart

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15
Q

where nutrient and waste exchange occurs

A

capillaries

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16
Q

vessels responsible for vasoconstriction and vasodilatation in th ebody

A

arterioles

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17
Q

venous part of systemic circulation

A

forits capacitance

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18
Q

Approximately ____ of the blood is stored in the veins

A

2/3

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19
Q

3 layers of vessels

A

tunica intima
tunica media
tunica adventitia

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20
Q

inner layer of blood vessel

A

tunica intima

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21
Q

blood vessel layer made of muscle and elastic tissue; arteries have a thicker layer

A

tunica media

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22
Q

outer layer of blood vessel

A

tunica adventitia

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23
Q

The _______ supplies the tunica adventitia with its own blood supply.

A

vasa vasorum

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24
Q

found in large blood vessels at the entrance

A

plug flow

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25
Q

The velocity profile of plug flow is _____

A

blunt

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26
Q

results when the red blood cells become chaotic and disorganized, resulting in assortment of velocities

A

turbulent flow

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27
Q

may occur from high-velocity flow and from tortuous or kinked vessels

A

turbulent flow

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28
Q

equation used to quantify the degree of turbulence in a blood vessel;

A

Reynolds number

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29
Q

A Reynolds number greater than ____ = true turbulence

A

2000

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30
Q

ties together relationship between vessel area, velocity of blood, and volume of blood flow

A

continuity equation

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31
Q

If an area of a vessel decreases, the velocity must _____

A

increase

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32
Q

states that an increase in velocity must be accompanied by a corresponding decrease in pressure

A

Bernoulli’s Principle

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33
Q

The inverse relationship between pressure and velocity is linked to the __________

A

law of conservation of energy

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34
Q

Any increase in velocity is an increase in energy, and therefore the pressure must ______ to preserve the total energy

A

decrease

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35
Q

describes the relationship between the volume of blood flow and the resistance to flow in a blood vessel

A

Pouiselle’s Law

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36
Q

equal to the difference in pressure divided by the resistance to flow in the vessel

A

flow

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37
Q

If the length of vessel or viscosity of blood increases, there is _______ flow

A

decreased

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38
Q

If the radius of a vessel increases, the flow _______

A

increases

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39
Q

If radius doubles, flow increases by a factor of ___

A

16

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40
Q

loss of energy in the form of heat

A

friction

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41
Q

flow is equal to the pressure differential divided by resistance

A

Ohm’s law

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42
Q

hemodynamically significant stenosis, decreased distal flow, leads to significant pressure gradient, cross-sectional area loss of 75%

A

critical stenosis

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43
Q

A 75% decrease in area corresponds to a __% decrease in diameter

A

50

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44
Q

resistance of the distal bed of blood vessels

A

effective resistance

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45
Q

sum of individual resistances when multiple vessels are connected in series

A

effective resistance

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46
Q

main contributors to the resistance in the cardiovascular system

A

arterioles

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47
Q

innervated walls can constrict or dilate in response to signals from the brain to either increase or decrease flow distally

A

arterioles

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48
Q

Is it more detrimental to have more than one stenosis in a vessel or a single substantial lesion in a vessel?

A

more than one stenosis in a vessel

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49
Q

Higher pressure proximal to a stenosis causes ______ to open up and the blood follows the lower-resistance path

A

collaterals

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50
Q

Veins located between the capillaries and the right atrium of the heart progressively get _____

A

larger

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51
Q

Pressure in venules

A

15 mmHg

52
Q

Pressure in the right atrium

A

0-8 mmHg

53
Q

Hydrostatic pressure at the heart

A

0 mmHg

54
Q

Below the heart, the hydrostatic pressure will be _____

A

positive

55
Q

folds of endothelial tissue inside of the veins

A

venous valves

56
Q

These provide a method to ensure forward flow

A

venous valves

57
Q

The difference between the pressure inside the vein and surrounding tissue

A

transmural pressure

58
Q

If the patient is supine, the transmural pressure will be ____

A

low

59
Q

If the patient is standing, the transmural pressure will ____

A

high

60
Q

Vein flow is ____

A

phasic

61
Q

variations that relate to respiration

A

phasic

62
Q

If there is pulsatility in peripheral veins, this may indicate problems with:

A

the right side of heart

63
Q

arteries that feed high resistance bed

A

triphasic or biphasic flow

64
Q

arteries that feed low resistance bed

A

monophasic flow

65
Q

distal arterioles dilate; increase in diameter of vessels accompanied by pressure drop

A

proximal stenosis

66
Q

seen in presence of proximal obstruction; delay in upstroke of systolic component

A

tardus parvus

67
Q

When sound impinges on a stationary reflector, the reflected frequency is identical to the transmitted, or incident frequency

A

Doppler Effect

68
Q

When a reflector is moving toward the transducer, the reflected frequency will be higher than the transmitted frequency and vice versa

A

Doppler Effect

69
Q

difference between transmitted and reflected frequencies

A

Doppler shift

70
Q

reflector is moving in a direction that is toward the transducer

A

positive shift

71
Q

reflector is moving in a direction that is away from the transducer

A

negative shift

72
Q

as frequency increases, intensity of scatter increases proportional to:

A

fourth power of frequency

73
Q

The higher the frequency, the ____ scatter, and the _____ attenuation

A

more
more

74
Q

As Doppler angle increases, the cosine of the angle _____

A

decreases

75
Q

Doppler angle and frequency shift are ______ related

A

inversely

76
Q

Most accurate Doppler shift

A

0 degrees

77
Q

As angle increases, frequency ______

A

decreases

78
Q

There is no Doppler shift at:

A

90 degrees

79
Q

determine positive or negative shift; permits bidirectional Doppler

A

phase quadrature

80
Q

There is no ____ resolution with CW Doppler

A

range

81
Q

compares transmitted and received frequencies

A

signal processor

82
Q

transmit time of CW

A

100%

83
Q

Duty factor CW

A

100%

84
Q

mathematical technique used to break down the signal and produce a spectral waveform

A

Fast Fourier Transform

85
Q

derived by tracing the spectral waveform from end diastole to end of next diastole

A

mean velocity

86
Q

used to quantitative the resistiveness of the distal vascular bed

A

Resistive Index

87
Q

used to determine how pulsatile a vessel is over time

A

Pulsatility Index

88
Q

estimate relative difference between systole and diastole

A

Pulsatility Index

89
Q

represents how many red blood cells are traveling at that velocity at a specific period of time

A

envelope

90
Q

wider range of velocities = ______ envelope

A

thicker

91
Q

The area under the envelope is the

A

spectral window

92
Q

turbulent flow that demonstrates a filling in of spectral envelope

A

spectral broadening

93
Q

transmits pulses of sound and waits for the sound to return in order to determine depth of returning echoes

A

Pulsed Wave Doppler

94
Q

Pulsed-Wave Doppler transmits anywhere from __-___ cycles per pulse

A

5-30

95
Q

The higher the pulse length, the ____ accurate sampling

A

more

96
Q

more accurately calculate the velocities from frequency shifts; shows what flow angle, so velocities can be accurately calculated

A

angle correction

97
Q

wraparound of the Doppler signal, where positive shifts are displayed as negative shifts

A

aliasing

98
Q

1/2PRF

A

Nyquist limit

99
Q

color representation of the Doppler shift information superimposed on grayscale imaging

A

Color Doppler Imaging

100
Q

provides information pertaining to both direction and mean velocity

A

Color Doppler Imaging

101
Q

processing technique used to obtain color flow information

A

Autocorrelation

102
Q

packet size is also known as:

A

ensemble length

103
Q

number of pulses per scan line within color gate

A

ensemble length

104
Q

The higher the ensemble length = the _____ the sensitivity

A

higher

105
Q

Packet size is typically __-__ pulses

A

10
20

106
Q

The best frame rate uses the _____ color gate

A

smallest

107
Q

BART

A

blue away red towards

108
Q

Three main components of Color Doppler Imaging:

A

hue
saturation
brightness

109
Q

the color itself determined by its wavelength

A

hue

110
Q

how much white is added compared to original color

A

saturation

111
Q

how intense the color is; related to amplitude of the signal

A

brightness

112
Q

wraparound of the color scale

A

aliasing

113
Q

Aliasing is eliminated by:

A

increasing the PRF/scale

114
Q

threshold for displaying color pixels instead of grayscale pixels

A

color priority

115
Q

smallest component of a 2D image

A

pixel

116
Q

flowing blood = ____ amplitude, ____ velocity signal

A

low
low

117
Q

uses low pass filter to eliminate the signal from the blood and only show color information representing wall motion

A

Tissue Doppler imaging

118
Q

frequency shift on which flow information is based is equal to 0 at that critical angle

A

Power Doppler

119
Q

ignores frequency shift and only focuses on the amplitude of the shift

A

Power Doppler

120
Q

inadvertent motion interrupts quality of signal

A

flash artifact

121
Q

used for measuring myocardial function

A

cardiac strain and strain rate

122
Q

changing of the shape of the muscle as it lengthens and contracts

A

strain

123
Q

permit evaluation of the deformation of the cardiac wall to evaluate for ventricular function

A

cardiac strain and strain rate

124
Q

method used to obtain strain information

A

speckle tracking

125
Q
A

Sonographic Topics (35 decks)

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