Term
The following factors relate to what type of doppler?
- range resolution
- sample volume
- limited maximum velocity (Nyquist)
- aliasing |
|
Definition
|
|
Term
The following factors relate to what type of doppler?
- range ambiguity
- region of overlap
- unlimited maximum velocity
- no aliasing |
|
Definition
|
|
Term
The following factors relate to what type of transducer?
- at least one crystal
- damped PZT
- low Q-factor
- wide bandwidth
- lower sensitivity |
|
Definition
Pulsed Doppler Transducer |
|
|
Term
The following factors relate to what type of transducer?
- at least two crystals
- undamped PZT
- high Q-factor
- narrow bandwidth
- higher sensitivity |
|
Definition
|
|
Term
The following factors relate to what general type of modality?
- normal incidence
- higher frequency
- pulsed wave only
- minimum of 1 crystal |
|
Definition
|
|
Term
The following factors relate to what general type of modality?
- 0/180 degrees
- lower frequency
- pulsed or CW
- min of 1 (pulsed) or 2 (CW) crystals |
|
Definition
|
|
Term
In this modality, velocity information is coded into colors and superimposed on a 2D grayscale, anatomic image |
|
Definition
|
|
Term
Is spectral doppler considered qualitative or quantitative? |
|
Definition
|
|
Term
Is color flow doppler considered qualitative or quantitative? |
|
Definition
|
|
Term
Since color flow doppler is based on ___ techniques, it has the same advantages (___) and disadvantage (___) |
|
Definition
Pulsed Wave
+ Range Resolution/Specificity
- Aliasing |
|
|
Term
What type of velocities does color doppler report? |
|
Definition
|
|
Term
What does RABT stand for? |
|
Definition
|
|
Term
What does BART stand for? |
|
Definition
|
|
Term
What type of velocities does PW and CW doppler report? |
|
Definition
|
|
Term
In color doppler, the color represents what? |
|
Definition
|
|
Term
What does black represent in color doppler? |
|
Definition
|
|
Term
Colors above the black stripe represent blood cells moving in what direction? |
|
Definition
|
|
Term
Colors below the black stripe represent blood cells moving in what direction? |
|
Definition
|
|
Term
Flow toward the transducer is what kind of doppler shift? |
|
Definition
|
|
Term
Flow away from the transducer is what kind of doppler shift? |
|
Definition
|
|
Term
Colors closer to the black stripe represent what? |
|
Definition
|
|
Term
Colors farther away from the black stripe represent what? |
|
Definition
|
|
Term
In addition to direction and velocity, what additional information does variance mode offer? |
|
Definition
Laminar vs Turbulent Flow |
|
|
Term
In variance mode, what do the colors on the left side represent? |
|
Definition
|
|
Term
In variance mode, what do the colors on the right side represent? |
|
Definition
|
|
Term
In color doppler, multiple pulses are used to accurately determine blood velocities. What are these multiple pulses called? |
|
Definition
|
|
Term
The following advantages apply to what type of packets/ensembles?
- more accurate velocity measurements
- more sensitive to low flow |
|
Definition
Larger Packets
Longer Ensemble Lengths |
|
|
Term
The following disadvantages apply to what type of packets/ensembles?
- more time needed to acquire data
- reduced frame rate
- decreased temporal resolution |
|
Definition
Larger Packets
Longer Ensemble Lengths |
|
|
Term
Flows detected at angles closer to 0 degrees will be ___ than those detected closer to 60 degrees |
|
Definition
|
|
Term
This modality only identifies the presence of a doppler shift, not speed or direction |
|
Definition
Power Doppler
Energy Mode
Color Angio |
|
|
Term
In this modality, the strength/amplitude of the reflected signal is processed, which is directly related to the number of moving blood cells |
|
Definition
Power Doppler
Energy Mode
Color Angio |
|
|
Term
What are 3 advantages of power doppler? |
|
Definition
1. increased sensitivity to low velocities
2. unaffected by doppler angles (unless 90 degrees exactly)
3. no aliasing |
|
|
Term
What are 3 disadvantages of power doppler? |
|
Definition
1. no velocity or direction information
2. lower frame rates / temporal resolution
3. susceptible to motion / flash artifacts |
|
|
Term
In addition to moving blood, very low frequency doppler shifts may be produced by ___ or ___ |
|
Definition
Moving Anatomy
Pulsating Vessels |
|
|
Term
On spectral displays, low frequency doppler shift artifacts called what? |
|
Definition
|
|
Term
On color displays, low frequency doppler shift artifacts are called what? |
|
Definition
|
|
Term
How is clutter or ghosting eliminated? |
|
Definition
|
|
Term
|
Definition
These exclude low frequency doppler shifts around the baseline, but have no effect on higher doppler frequency shifts commonly created by blood cell motion |
|
|
Term
|
Definition
| This is a special form of mirror image artifact that only appears with spectral doppler; while the flow pattern appears identical above and below the baseline, the true pattern in unidirectional |
|
|
Term
The following cause what type of artifact?
- doppler receiver gain too high
- incident angle near 90 degrees between the beam and the flow direction |
|
Definition
|
|
Term
This is the tool that breaks up a complex signal into the individual velocities which make up the reflected doppler signal |
|
Definition
|
|
Term
FFT (Fast Fourier Transform)
|
|
Definition
This doppler analysis tool is exceedingly accurate and displays all individual velocity components from the reflected signal; it is used with PW and CW doppler |
|
|
Term
Using FFT, a laminar flow will produce what in the display? |
|
Definition
|
|
Term
Using FFT, a turbulent flow will produce what in the display? |
|
Definition
|
|
Term
This doppler analysis tool is less accurate but substantially faster than FFT; it is used with color flow doppler |
|
Definition
Autocorrelation
Correlation Function |
|
|
Term
When the spectral window is filled in, this is called what? and results from what? |
|
Definition
Spectral Broadening
Turbulent Flow |
|
|
Term
Can a patient be so severely anemic that a doppler exam cannot be performed? |
|
Definition
|
|
Term
Is FFT quantitative or qualitative? |
|
Definition
|
|
Term
Is autocorrelation quantitative or qualitative? |
|
Definition
|
|
Term
|
Definition
This ratio is a quantitative, doppler-derived measurement of the vascular resistance of a segment of the arterial system. It requires min/max velocities |
|
|
Term
|
Definition
This ratio is a quantitative, doppler-derived measurement of the vascular resistance of a segment of the arterial system. It requires min/mean/max velocities |
|
|
Term
The following are advantages of what?
- based on mathematical measurements
- based on waveform shapes; unaffected by doppler angles |
|
Definition
Resistivity Index (RI)
Pulsatility Index (PI) |
|
|
Term
The doppler effect is presented as a ___ when the source and the receiver are ___ |
|
Definition
Frequency Shift
Moving relative to each other |
|
|
Term
Starting from the same point, the sound source is moving east at 12 miles/hour and the receiver is moving west at 10 miles/hour. The doppler shift is ___ |
|
Definition
|
|
Term
Starting from the same point, the receiver is moving west at 12 miles/hour and the source is moving west at 10 miles/hour. The doppler shift is ___ |
|
Definition
|
|
Term
Doppler shift produces information about ___ |
|
Definition
|
|
Term
At what angle between the sound beam and the direction of motion will the doppler shift be at a maximum? |
|
Definition
|
|
Term
At what angle between the beam and the direction of motion will the doppler shift be a minimum? |
|
Definition
|
|
Term
What is the difference between speed and velocity? |
|
Definition
Speed = magnitude
Velocity = magnitude & direction |
|
|
Term
What is the current method of processing doppler signals? |
|
Definition
FFT for spectral doppler
Autocorrelation for color doppler |
|
|
Term
What is the typical range of doppler shift found in diagnostic imaging? |
|
Definition
20 Hz - 20 kHz (in the audible range) |
|
|
Term
The phenomenon where high velocities appear negative is called what? |
|
Definition
|
|
Term
The frequency at which aliasing occurs is called what? |
|
Definition
|
|
Term
The area of interrogation in a pulsed doppler exam is called what? |
|
Definition
|
|
Term
T/F: the higher the emitted frequency, the more likely a pulsed wave signal is to alias |
|
Definition
|
|
Term
T/F: shallower sample volumes result in more aliasing |
|
Definition
|
|
Term
T/F: only pulsed wave doppler exams have a sample volume |
|
Definition
|
|
Term
An 8 MHz transducer with a PRF of 5,000 Hz is imaging to a depth of 7 cm. What is the Nyquist frequency?
A. 4 MHz
B. 3.5 Hz
C. 2.2 kHz
D. 2.5 dB
E. 5 kHz |
|
Definition
|
|
Term
An 8 MHz transducer with a PRF of 5,000 Hz measures a doppler shift of 7 kHz. The study is repeated with a 4 MHz transducer. What doppler shift will be measured?
A. 4 MHz
B. 3.5 Hz
C. 4 kHz
D. 3.5 dB
E. 3,500 Hz |
|
Definition
|
|
