Chapter 5 Flashcards

(53 cards)

1
Q

Autocorrelation

A

a rapid technique, used in most color Doppler instruments; to obtain mean Doppler shift frequency

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2
Q

baseline shift

A

movement of the zero Doppler shift frequency or zero flow speed line up or down on a spectral display

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3
Q

Bernoulli effect

A

pressure reduction in a region of high flow speed

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4
Q

bidirectional

A

indicating Doppler instruments capable of distinguishing between positive and negative Doppler shifts

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5
Q

clutter

A

noise in the Doppler signal that generally is caused by high amplitude, Doppler shifted echoes from the heart or vessel walls.

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6
Q

color- Doppler display

A

the display that is presented in color

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7
Q

compliance

A

Distensibility; nonrigid stretch-ability of vessels

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8
Q

continuous wave doppler

A

a Doppler device or procedure that used continuous wave ultrasound

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9
Q

cosine

A

the length of side B divided by the length of side C

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10
Q

disturbed flow

A

flow that cannot be described by straight, parallel streamlines

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11
Q

Doppler angle

A

the angle between the sound beam and the flow direction

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12
Q

Doppler effect

A

a change in frequency caused by reflector motion

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13
Q

Doppler equation

A

the math description of the relationship between the Doppler shift, frequency, Doppler angle, propagation speed, and reflector speed

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14
Q

Doppler-power display

A

color Doppler display in which colors are assigned according to the strength

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15
Q

Doppler shift

A

reflected frequency minus incident frequency, the change in frequency caused by motion

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16
Q

Doppler spectrum

A

the range of freq present in Doppler shifted echoes

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17
Q

duplex instrument

A

an ultrasound instrument that combines gray scale sonography with pulsed Doppler and possibly CW doppler

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18
Q

eddies

A

regions of circular flow patterns present in turbulence

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19
Q

ensemble length

A

number of pulses used to generate one color Doppler image scan line

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20
Q

fast Fourier transform

A

digital computer implementation of the Fourier transform

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21
Q

filter

A

an electric circuit that passes frequencies within a defined range

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22
Q

fluid

A

a material that flows and conforms to the shape of its container; gas or liquid

23
Q

flow

A

to move in a stream; volume flow rate

24
Q

frequency spectrum

A

the range of Doppler shift frequencies present in the returning echoes

25
gate
a device that allows only echoes from a selected depth arrival time to pass
26
hue
the color perceived based on the frequency of light
27
inertia
resistance to acceleration
28
laminar flow
flow in which fluid levels slide over each other in a smooth, orderly manner, with no mixing between layers
29
luminance
brightness of presented hue and saturation
30
parabolic flow
laminar flow with a profile in the shape of a parabola
31
phase quadrature
two signals differing by one fourth of a cycle
32
plug flow
flow with all fluid portions traveling with the same flow speed and direction
33
poise
unit of velocity
34
Poiseuille equation
the dependence of volume flow rate on pressure, vessel length and radius, and fluid viscosity
35
priority
the gray scale echo strength below which color Doppler info is shown on a display
36
pulsatile flow
flow that accelerate and decelerates with each cardiac cycle
37
pulsed doppler
a Doppler device or procedure that uses pulsed wave ultrasound
38
range gating
selection of the depth from which echoes are accepted based on echo arrival time
39
resistance
pressure difference divided by volume flow rate for steady flow
40
sample volume
the anatomic region from which pulsed Doppler echoes are accepted
41
saturation
the amount of hue present in a mix with white
42
spectral analysis
separation of freq in a Doppler signal for display as a Doppler spectrum.
43
spectral broadening
the widening of the Doppler shift spectrum
44
spectral Doppler display
the presentation of Doppler info in a quantitative form of Doppler shift verses time
45
spectrum analyzer
a device that derives a freq spectrum from a complex signal
46
stenosis
narrowing of a vessel lumen
47
streamlines
a line representing the path of motion of a particle of fluid
48
turbulence
random, chaotic, multi-directional flow of a fluid with mixing between layers, flow that is not laminar
49
variance
square of standard deviation one of outputs of the auto-correlation process.
50
viscosity
resistance of a fluid to flow
51
volumetric flow rate
volume of fluid passing a point per unit of time
52
wall filter
an electric filter that passes freq above a set level and eliminates strong, low freq Doppler shifts from pulsating heart or vessel walls or tissue motion
53
window
an anechoic region appearing beneath echo frequencies presented on a Doppler spectral display