Chapter 5 Kremkau Flashcards
a rapid technique used in most color-Doppler instruments to obtain mean Doppler-shift frequency
autocorrelation
movement of the zero Doppler-shift frequency or zero flow speed line up or down on a spectral display
baseline shift
pressure reduction in a right of high flow speed
Bernouth effect
indicating Doppler instruments capable of distinguishing between positive and negative Doppler shifts (approaching and receding flow)
bidirectional
noise in the Doppler signal that generally is caused by high amplitude. Doppler shifted echoes from the heart or vessel walls
clutter
the presentation of two dimensional real time Doppler shift information in color superimposed on a real time gray scale anatomic cross-sectional image
Flow directions toward and away from the heart are presented as different colors on the display
color-Doppler display
distensibility; nonrigid stretchability of vessels
compliance
A Doppler device or procedure that uses continuous-wave ultrasound
continuous-wave Doppler
the cosine of angle A in figure C. the length of side B divided by the length of side C.
cosine
flow that cannot be described by straight parallel streamlines
disturbed flow
the angle between the sound beam and the flow direction
Doppler angle
a change in frequency caused by reflector motion
Doppler effect
The mathematical description of the relationship between the Doppler shift, frequency, Doppler angle, propagation speed, and reflector speed
Doppler equation
Color-doppler display in which colors are assigned according to the strength (amplitude, power, intensity, energy) of the Doppler shifted echoes
Doppler-power display
Reflected frequency minus incident frequency; the change in frequency caused by motion
Doppler-shift
the range of frequencies present in Doppler shifted echoes
doppler spectrum
an ultrasound instrument that combines grayscale sonography with pulsed-Doppler and, possibly, continuous-wave Doppler
Duplex instrument
regions of circular flow patterns present in turbulence
eddies
number of pulses used to generate one color-Doppler image scan line
ensemble length
digital computer implementation of the Fourier transform
Fast Fourier transform
an electric circuit that passes frequencies within a defined range
filter
to move in a stream; volume flow rate
flow
a material that flows and conforms to the shape of its container, a gas or liquid
fluid
the range of Doppler-shift frequencies present in the returning echoes
frequency spectrum
a device that allows only echoes from a selected depth (arrival time) to pass
gate
the color perceived based on the frequency of light
hue
resistance to acceleration
inertia
flow in which fluid layers slide over each other in a smooth, orderly manner, with no mixing between layers
laminar flow
brightness of a presented hue and saturation
luminance
laminar flow with a profile in the shape of a parabola
parabolic flow
two signals differing by one-fourth of a cycle
phase quadrature
flow with all fluid portions traveling with the same flow speed and direction
plug flow
unit of viscosity
poise
the mathematical description of the dependance of volume flow rate on pressure, vessel length and radius, and fluid viscosity
poiseuille equation
the gray scale echo strength below which color-Doppler information is shown preferentially on a display
priority
flow that accelerates and decelerates with each cardiac cycle
pulsatile flow
a doppler device or procedure that uses pulsed-wave ultrasound
Pulsed Doppler
selection of the depth from which echoes are accepted based on echo arrival time
range gating
pressure difference divided by volume flow rate for steady flow
resistance
the anatomic region from which pulsed Doppler echoes are accepted
sample volume
the amount of hue present in a mix with white
saturation
separation of frequencies in a Doppler signal for display as a Doppler spectrum; the application of the Fourier transform to determine the frequency components present in a Doppler signal
spectral analysis
the widening of the Doppler-shift spectrum; that is, the increase in the range of Doppler-shift frequencies present that occurs because of a broadened range of flow velocities encountered by the sound beam. This occurs for disturbed and turbulent flows
spectral broadening
the presentation of Doppler information in a quantitative form of Doppler shift versus time. Visual display of doppler spectrum
Spectral-Doppler display
a devices that derives a frequency spectrum from a complex signal
spectrum analyzer
narrowing of a vessel lumen
stenosis
a line representing the path of motion of a particle of fluid
streamlines
random, chaotic, multidirectional flow of a fluid with mixing between layers; flow that is not laminar
turbulence
square of standard deviation; one of the outputs of the autocorrelation process; a measure of spectral broadening
variance
resistance of a fluid to flow
viscosity
volume of fluid passing a point per unit of time
volumetric flow rate
an electric filter that passes frequencies above a set level and eliminates strong, low-frequency Doppler shifts from pulsating heart of vessel walls or tissue motion
wall filter
an anechoic region appearing beneath echo frequencies presented on a Doppler spectral display
window
The ____ are the tiniest vessels in the circulatory system.
capillaries
In which of the following can Doppler ultrasound detect flow?
a. the heart
b. the arteries
c. arterioles
d. capillaries
e. venules
f. veins
a, b ,f
The flow is to move in a ____.
stream
The characteristic of a fluid that offers resistance to flow is called ______.
viscosity
Poise is a unit ______.
viscosity
Pressure is ______ per unit area.
force
Pressure is ______.
omnidirectional
Flow is a response to pressure ______ or _____.
difference, gradient
If the pressure is greater at one end of a liquid filled tube or vessel that it is at the other, the liquid will flow from the ______ - pressure end to the ______ -pressure end
higher, lower
Which of the following are parts of the circulatory system?
a. heart
b. cerebral ventricle
c. artery
d. arteriole
e. capillary
f. bile duct
g. venule
h. vein
a c d e g h
The ______ are the tiniest vessels in the circulatory system.
capillaries
In which of the following can Doppler ultrasound detect flow?
a. the heart
b. arteries
c. arterioles
d. capillaries
e. venules
f. veins
a b f
to flow is to move in a
stream
The characteristic of a fluid that offers resistance to flow is called _____.
viscosity
Poise is a unit of _____.
viscosity
Pressure is ______ per unit area.
force
Pressure is ______.
omnidirectional
Flow is a response to pressure ______ or _____.
difference, gradient
If the pressure is greater at one end of a liquid-filled tube or vessel that it is at the other, the liquid will flow from the _____-pressure end to the ______- pressure.
higher, lower
Flow increases if ______ increase(s).
pressure difference and gradient
While flow resistance increases, volumetic flow rate
decreases
If pressure difference is doubled, volumetric flow rate is
doubled
If flow resistance is doubled, volumetric flow rate is
halved
Flow resistance in a vessel depends on
a. vessel length
b. vessel radius
c. blood viscosity
d. all of the above
e. none of the above
d
Flow resistance decreases with an increase in
vessel radius
Flow resistance depends most strongly on ____
vessel radius
Volumetric flow rate decreases with an increase in
vessel length
blood viscosity
When the speed of a fluid is constant across a vessel, the flow is called _____ flow.
plug
_____ flow occurs when straight parallel steamlines describing the flow are altered.
disturbed
_____ flow involves random and chaotic flow patterns, with particles flowing in all directions
turbulent
When the speed of a fluid is constant across a vessel, the flow is called _____ flow.
plug
Turbulent flow is more likely _____ to a stenosis.
distal
A narrowing of the lumen of a tube is called a ______.
stenosis
Proximal to, at, and distal to a stenosis, _____ must be constant
volumetric flow rate
Poiseuille equation predicts a(n) ______ in flow speed with a decrease in vessel radius.
decrease
The continuity rule predicts a(n) ______ in flow speed with a decrease in vessel radius.
increase
In a stenosis, the pressure is ______ the proximal and distal values.
less than
Added forward flow and flow reversal in diastole can occur with ______ flow.
pulsatile
While stenosis diameter decreases, ______ pass(es) through a maximum.
flow speed at the stenosis and the Doppler shift at the stenosis
The ______ effect is used to detect and measure ______ in vessels.
Doppler, flow
Motion of an echo-generating structure causes an echo to have a different ______ from that of the emitted pulse.
frequency
If the incident frequency is 1 MHz, the propagation speed is 1600 m/s, and the reflector speed is 16 m/s toward the source, the Doppler shift is _____ MHz, and the reflected frequency is _____ MHz.
0.02, 1.026
If a 2 MHz ultrasound is reflected from a soft tissue boundary moving at 10 m/s toward the source, the Doppler shift is ____ Hz.
0.026
If a 2 MHz ultrasound is reflected from a soft tissue boundary moving at 10 m/s away from the source, the Doppler shift is _____ MHz.
-0.026
The Doppler shift is the difference between _____ and ______ frequencies.
received and emitted
When incident sound direction and reflector motion are not parallel, calculation of the reflected frequency involves the ______ of the angle between these directions.
cosine
For an operating frequency of 2 MHz, a flow speed of 10 cm/s toward, and a Doppler angle of 0 degrees, calculate the Doppler shift (kHz)
0.26
For an operating frequency of 6 MHz, a flow speed of 50 cm/s, and a Doppler angle of 60 degrees, calculate the Doppler shift
1.95
