Physics 2 Quiz 3 (Doppler) Flashcards
Which mode provides precise information regarding the variation in velocities present at a selected location in the field?
Pulsed Doppler with spectral analysis
What is the Doppler angle?
Flow direction relative to the ultrasound beam
Spectral broadening will cause which change in a spectral analysis tracing?
Vertical thickening
When frequency is reduced, what happens to the Doppler shift frequency from a moving tissue?
It decreases
When imaging w color flow Doppler where the pulse repitition frequency is 12 kHz, aliasing would first become apparent once the Doppler shift becomes greater than:
6 kHz
In diagnostic ultrasound, what does the Fast Fourier Transform (FFT) do?
Separate the frequency components of a Doppler shift signal
Continuous wave Doppler…
Simultaneously transmits and receives ultrasound
Term that relates to the intensity of a color Doppler image:
Luminance
In general, a Doppler frequency shift could result from all of the following EXCEPT:
—a stationary sound source and a stationary listener
—a moving sound source and a stationary listener
—a moving sound source and a moving listener
—a stationary sound source and a moving listener
—a stationary sound source and a stationary listener
T/F
The intensity of the returning Doppler shift echoes are affected by the flow speed
False
***Written
What is the Doppler shift frequency i you had an initial frequency of a 4 MHz and received frequency of 4.05 MHz
50 kHz
To precisely obtain the velocity of the carotid artery, the ______________ ______________ must be accurately incorporated
Doppler angle
T/F
Power Doppler does not rely on the velocity of the reflector and is not angle dependent
True
The Doppler equation relates the Doppler shift to the:
Flow speed, frequency, and Doppler angle
Color can change in a vessel due to:
Vessel contour, increase in flow speed, change in Doppler angle
Color Doppler…
-demonstrates flow direction
-demonstrates flow characteristics
-angle dependence
-demonstrates mean Doppler shift
What is (are) required in a color Doppler signal processor?
-Detecting whether the shift is positive or negative
-Using autocorrelation
-Ability to detect Doppler shift
(All are required)
A color Doppler display of red signifies:
Doppler shifts that depend on the map chosen
Color map baselines are represented by:
Black
A wall filter might…
Eliminate high-intensity Doppler shifts
T/F
Pulsed wave and color Doppler combined with gray-scale sonography is called duplex scanning
False
When compared to gray-scale frame rates, color-flow frame rates are:
Lower
What processing technique can cause pixilation ?
Read zoom
T/F
Aliasing happens with spectral Doppler but not color Doppler
False
There are multiple adjustments that need to made to the image below. List the primary adjustment that needs to be made for each of the following:
—grey scale image
—spectral analysis
—color Doppler
Do not list more than one thing for each mode. Only the frst statement will be read.
grey scale - decrease the depth
spectral analysis - decrease the PRF
color Doppler - angle vessel in the direction of the color box and Doppler angle
Power Doppler imaging is a good choice when you want to:
Show minute perfusion
Which of the following represents the greatest frequency shift?
1.2 kHZ
-2.1 kHz
0.002 MHz
-3,200 Hz
-0.003 MHz
-3,200 Hz
If the angle correct is set at 0º but should be 60° and the display indicates a flow speed of 100 cm/s, what would be the correct flow speed?
50 cm/s
cosine was 1 but should have been 0.5
multiply velocity by 0.5
Decreased distal resistance normally has what effect on end-diastolic flow?
Increase in flow
If all the cells in a vessel were moving at the same constant speed, the Doppler spectral trace would be:
A thin horizontal line
