Chapter 5 Flashcards
Autocorrelation
A rapid technique used in most color doppler instruments
Baseline Shift
Movement of the zero doppler shift frequency or or zero flow speed line up or down the spectral display
Bernouille Effect
Pressure reduction in a region of high low speed
Bidirectional
Indicating doppler instruments capable of distinguishing between positive and negative doppler shifts
Clutter
Noise in the doppler signal that generally is caused by amplitude
Color Doppler Display
The presentation of 2d real time doppler shift info on color superimposed on a gray scale image
Compliance
Distensibility
Continuous Wave Doppler
A doppler device or procedure that uses continuous wave ultrasound
Cosine
The cosine of angle A in figure c is the length of side b divided by the length of side c
Disturbed Flow
Flow that cannot be described by straight parallel streamlines
Doppler Angle
The angle between the sound beam and the flow direction
Doppler Effect
A change in frequency caused by reflector motion
Doppler Equation
Mathematical description of the relationship between doppler shift frequency doppler angle prop speed and reflector speed
Doppler-Power display
Color doppler display in which colors are assigned according to the strength
Doppler Shift
Reflected freq minus incident freq; the change in frequency caused by motion
Doppler Spectrum
The range of frequencies present in doppler shifted echoes
Duplex Instrument
An ultrasound instrument that combines gray scale imaging sonography with pulsed doppler
Eddies
Regions of circular flow patterns present in turbulence
Ensemble Length
Number of pulses used to generate one color doppler image scan line
Fast Fourier Transform
Digital computer implementation of the Fourier transform
Filter
An electric circuit that passes frequencies within a defined range
Flow
To move in a steam
Fluid
A material that flows and conforms to the shape of a container
Frequency Spectrum
The range of doppler shift frequencies present in returning echoes
Gate
A device that allows only echoes from a selected depth to pass
Hue
The color perceived based on the frequency of light
Inertia
Resistance to acceleration
Laminar Flow
Flow in which fluid layers slide over each other in a smooth orderly manner
Luminance
Brightness of a presented hue
Parabolic Flow
Laminar flow with a profile in the shape of the parabola
Phase Quadrature
Two signals differing by one fourth of a cycle
Plug Flow
Flow with all fluid portions
Poise
Unit of viscosity
Poiseuille Equation
The description of the dependence of volume flow rate on pressure vessel length and radius
Priority
The gray scale echo strength below which color doppler is shown preferentially on a display
Pulsatile Flow
Flow that accelerates and decelerates with each cardiac cycle
Pulsed Doppler
A doppler device or procedure that uses pulsed wave ultrasound
Range Gating
Selection of the depth from which echoes are accepted based on echo arrival time
Resistance
Pressure difference divided by volume flow rate for steady flow
Sample Volume
The anatomic region from which pulsed doppler echoes are accepted
Saturation
The amount of hue present in a mix with with white
Spectral Analysis
Separation of frequencies in a doppler signal for display as a doppler spectrum
Spectral Broadening
The widening of the doppler shift spectrum
Spectral Doppler Display
The presentation of doppler info in a quantitative form of doppler shift versus time
Spectrum Analyzer
A device that derives a frequency spectrum from a complex signal
Stenosis
Narrowing of a vessel lumen
Streamlines
A line representing the the path of motion of a particle of motion
Turbulence
Random chaotic multi-directional flow of fluid with mixing between layers
Variance
Square the standard, one of the outputs of the autocorrection process
Viscosity
Resistance of a fluid to flow
Volumetric Flow Rate
Volume of fluid passing a point per unit of time
Wall Filter
An electric filter that passes frequencies above a set level and eliminates strong low frequency doppler shifts
Window
An anechoic region appearing beneath echo frequencies presented on a doppler spectral display
