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 Which one of the following is true about color map 1?
A. Red indicates turbulent flow
B. Blue indicates turbulent flow
C. Blue indicates laminar flow away from the transducer
D. Red indicates flow away from the transduer
E. Red indicates flow toward the transducer
E. Red indicates flow toward the transducer (this multiple choice question has been scrambled)
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Which one of the following is true about color map 1?
A. Blue indicates flow toward the transducer
B. Blue indicates laminar flow away from the transducer
C. Red indicates flow away from the transducer
D. Blue indicates flow away from the transducer
E. Blue indicates turbulent flow
D. Blue indicates flow away from the transducer (this multiple choice question has been scrambled)
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Which of the following is true about color map 2?
A. blue indicates flow toward the transducer
B. dark blue indicates laminar flow away from the transducer
C. blue indicates flow away from the transducer
D. red indicates turbulent flow
E. light blue indicates turbulent flow
C. blue indicates flow away from the transducer (this multiple choice question has been scrambled)
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Which of the following is true about color map 2?
A. green indicates higher volume flow toward the transducer
B. green indicates higher velocity flow toward the transducer
C. red indicates turbulent flow
D. blue indicates laminar flow away from the transducer
E. red indicates flow away from the transducer
B. green indicates higher velocity flow toward the transducer (this multiple choice question has been scrambled)
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Which statement is true about color map 1?
A. red indicates turbulent flow
B. blue indicates turbulent flow
C. green indicates laminar flow away from the transducer
D. red and yellow indicate flow toward the transducer
E. red indicates flow away from the transducer
D. red and yellow indicate flow toward the transducer (this multiple choice question has been scrambled)
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Which statement is true about color map 1?
A. red and yellow indicate flow away from the transducer
B. red indicates flow away from the transducer
C. blue indicates turbulent flow
D. green indicates turbulent flow away from the transducer
E. red indicates turbulent flow
D. green indicates turbulent flow away from the transducer (this multiple choice question has been scrambled)
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Which statement is best reason why color map 1 is a variance mode map?
A. blue indicates flow away from transducer
B. red indicates flow toward transducer
C. red indicates turbulent flow
D. blue and green indicate flow away from transducer
E. yellow indicates flow away from transducer
D. blue and green indicate flow away from transducer (this multiple choice question has been scrambled)
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Which statement is true about color map 2?
A. light blue indicates flow toward the transducer
B. red indicates turbulent flow
C. dark blue indicates laminar flow away from transducer
D. red indicates flow away from transducer
E. dark blue indicates turbulent flow
C. dark blue indicates laminar flow away from transducer (this multiple choice question has been scrambled)
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Which statement is true about color map 2?
A. light blue indicates laminar flow toward transducer
B. red indicates turbulent flow
C. red indicates turbulent flow toward transducer
D. red indicates flow away from transducer
E. light blue indicates turbulent flow
E. light blue indicates turbulent flow (this multiple choice question has been scrambled)
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In which direction does blood flow through the top of the vessel?
A. left to right
B. left to right, then right to left
C. rigth to left
D. right to left, then left to right
A. left to right (this multiple choice question has been scrambled)
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What does the black area in the center of both vessels represent?
A. zero Doppler shift
B. a clot
C. no flow
D. a disection
E. all of the above
A. zero Doppler shift (this multiple choice question has been scrambled)
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In which direction is blood flowing through the vessel?
A. right to left, then left to right
B. right to left
C. left to right, then right to left
D. left to right
B. right to left (this multiple choice question has been scrambled)
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The Doppler effect is presented as a ___________ when the sourse and the receiver are ___________.
frequency shift, in motion relative to each other
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Starting from the same point, the sound source is moving toward the East at 12 miles/hour and the receiver is moving toward the West at 10 miles/hour. The Doppler shift is __________. (+ or -)
negative, because source and reciever are moving farther apart
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Starting from the same point, the receiver is moving toward the West at 12 miles/hour and the source is moving toward the West at 10 miles/hour. The Doppler shift is __________. (+ or -)
negative, because the source and receiver are moving further apart
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Doppler shift produces information about __________.
velocity
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At what angle between the sound beam and the direction of motion will the Doppler shift be a maximum?
0 or 180 degrees (the sound beam and the direction of motion should be parallel)
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At what angle between the sound beam and the direction of motion will the Doppler shift be a minimum?
90 degrees. no Doppler frequency exists becuase the cosine of 90 degrees is zero.
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What is the difference between speed and velocity?
speed has only a magnitude. velocity has magnitude and direction
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What is the current method of processing Doppler signals?
Fast Fourier Transform (FFT) method of spectral analysis is used for pulsed and CW. Autocorrelation is the method of spectral analysis for color flow Doppler.
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What is the typical range of Doppler shift found in diagnostic imaging examinations?
between 20 Hz and 20 kHz (in the audible range)
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The phenomenon where high velocities appear negative is called __________.
aliasing
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The frequency at which aliasing occurs is called __________.
Nyquist limit
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The are of interrogation in a pulsed Doppler exam is called __________.
sample volume
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True or False.
The higher the emitted frequency, the more likely a pulsed wave signal is to alias.
True
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True or False.
Shallower sample volumes result in more aliasing.
False
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True or False.
Only pulsed wave Doppler exams have a sample volume.
True
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An 8 MHz transducer with a pulse repetition frequency 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
- C. 2.2 kHz
- Nyquist limit is one-half of the pulse repetition frequency, 2.5 kHz or 2,500 Hz
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An 8 MHz transducer with a PRF of 5000 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. 3500 Hz
- E. 3500 Hz
- measured Doppler shift is directly related to transducer frequency
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