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65 Cards in this Set
- Front
- Back
___is a form of two dimensional Doppler?
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color flow
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____is coded into colors and superimposed on a two dimensional grayscale, anatomic image?
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velocity information
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black and white identifies_____, but color identifies ____?
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anatomic structures...blood flow velocities and function
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color Doppler provides___?
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1. pulsed ultrasound technique
2. range resolution (range specificity) 3. subject to aliasing |
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color Doppler provides information regarding____?
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direction of flow and semi-quantitative
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Color Doppler reports___?
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average velocities or mean velocities
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pulse and continuous wave Doppler reports___?
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peak velocities
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color Doppler uses____or lookup table to convert____ into colors, with black region in the center?
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dictionary...measured velocity
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the two most commonly used dictionaries are called?
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1. velocity mode
2. variance mode |
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color present information on____?
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flow direction
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black region in the middle of the color map indicate____?
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no Doppler shift
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color above the black stripe indicate cell moving toward the transducer or____?
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positive Doppler shift
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multiple color closer to black stripe indicate___?
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lower velocity
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colors higher above the black stripe indicates___?
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higher velocity
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the color below the black stripe indicate blood cell moving___?
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away from the transducer
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multiple color closer to the black stripe indicates___?
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lower velocity
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colors farther below the black stripe indicates__?
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faster velocities
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with the velocity mode map, the color change____?
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up and down (no side to side)
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____ mode distinguishes ____from turbulent flow?
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variance...laminar flow
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color in a variance and____ mode map indicates____?
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velocity...flow direction
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the variance mode maps display___?
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different color side to side
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in variance map, color from the left side indicates___?
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laminar flow (normal)
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in variance map, color from the right side indicate___?
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turbulent flow (asso. w/ pathology)
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multiple ultrasound pulses determine____?
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blood cell velocities
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____ or ensemble (multiple pulses) determine___ of the blood cell?
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packet...velocity
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larger packets or longer ensemble lengh (large pulses) have 2 advantages___?
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1. more accurate velocity measurement
2. more sensitive to low flow |
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packet with more pulses also have disadvantages___?
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1. more time
2. reduce frame rate 3. decrease temporal resolution |
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color Doppler measures___?
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mean velocity
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spectral Doppler (pulsed and continuous wave) measures__?
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peak velocity
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power mode Doppler only identifies_____?
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the presence of a Doppler shift
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Power mode Doppler does not evaluate___?
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speed or direction
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Power mode Doppler is___?
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non-directional color Doppler
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all the vessels in the power Doppler image have the same__?
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color
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power Doppler also called?
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energy mode or color angio
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traditional Doppler such as pulsed, continuous, color process____?
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velocity information
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in power mode, _____of the reflected signal is processed regardless speed or direction?
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the strenght or amplitude
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_____directly related to the number of moving blood cells?
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the amplitude of the reflection
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three advantages in power mode?
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1. increase sensitivity to low flow
2. unaffected by Doppler angles, unless 90 degree 3. no aliasing |
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three disadvantage in power mode?
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1. no measurement of velocity or direction
2. lower frame rate than color flow Doppler 3. susceptible to motion of the transducer, burst color, flash artifact |
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on spectral display, low frequency Doppler shift artifact called___?
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clutter
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on spectral display, low frequency with color Doppler shift called___?
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ghosting artifact
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____is used to eliminate low frequency Doppler shifts resulting form moving anatomy rather than moving blood cells?
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wall filter
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wall filters exclude____ shift around the baseline of a spectral display?(but no effect on higher Doppler frequency)
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low frequency Doppler
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with color Doppler,_____eliminate color arising from slow velocity?
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wall filters
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mirror image artifact arises only with spectral Doppler, called?
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crosstalk
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crosstalk appears_______ the base line?
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above and below
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flow pattern in crosstalk is ___?
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unidirectional, but appears bidirectional
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2 things cause crosstalk
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1. Doppler receiver gain too high
2. incident beam near 90 degree between sound beam and flow direction |
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_____is a tool that breaks the ____ into its basic building block and identifies individual velocity?
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spectral analysis...complex signal
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2 method of spectral analysis?
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1. Fast Fourier Transform (FFT)
2. Autocorrelation |
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early methods of Doppler analysis include___?
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zero crossing detector, Chirp-Z transform, and time interval histogram (not for computer)
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_____a digital technique used to process both____ and ____ wave Doppler signal?
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Fast Fourier Transform (FFT)...pulsed...continous
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FFT has 2 advantages?
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1. exceeding accurate
2. individual velocity that make up complex reflected signal |
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spectral display of the FFT distinguishes_____from____?
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laminar flow, turbulent flow
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with laminar flow, most cells travel at___?
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similar velocities
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the region between the baseline and the spectrum called___?
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spectral window
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with blood in chaotic, and many different direction and speed, the pulsed Doppler spectral______filled in by___?
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window, turbulent flow
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_____wider range of velocities and Doppler shifts within the sample volume?
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spectral broadening
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____is the digital to analyze____?
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autocorrelation... color flow Doppler
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____used with color Doppler because of lot data being processed?
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autocorrelation
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_______or percentage of blood composed of red blood cell, normally 45%
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hematocrit
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Doppler spectrum displays the blood_____throughout the entire cardiac cyle
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velocities
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an arterial Doppler waveform is____?
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pulsatile
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____is useful in establishing the diagnosis of arterial stenosis?
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resistivity index (RI)
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RI and pulsatility Index (PI) have advantages?
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1. mathematical measurement
2. the shape of the Doppler spectrum |