Chapter 19 Flashcards
Which of the following is true about color map 1?
Red indicated flow towards the transducer
Which one of the following is true about map 1?
Blue indicated flow away from the transducer
Which of the following is true about color map 2?
Blue indicates flow away from the transducer
Which of the following is true about color map 2?
Green indicates higher velocity flow toward the transducer
Which statement is true about color map 1?
Red and yellow indicate flow toward the transducer
Which statement is true about color map 1?
Green indicates turbulent flow away from the transducer
Which statement is the best reason why color map 1 is a variance mode map?
Blue and green indicate flow away from the transducer
Which statement is true about color map 2?
Dark blue indicates laminar flow away from the transducer
Which statement is true about color map 2?
Light blue indicates turbulent flow
In which direction does blood flow through the top vessel?
Left to right
What does the black area (yellow area) in the center of both vessels represent?
Zero doppler shift
In which direction is blood flowing through the vessel?
Right to left
The doppler effect is presented as a _______ when the source and receiver are _______.
Frequency shift
In motion relative to each other
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 _________.
Negative
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 _________.
Negative
Doppler shift produces information about ________
Velocity
At what angle between the sound beam and the direction of the motion will the doppler shift be the highest?
0 degrees to 180 degrees
At what angle between the sound beam and the direction of the motion will the doppler shift be the closest to 0?
90 degrees
What is the difference between speed and velocity?
Speed has only a magnitude. Velocity has magnitude and direction.
What is the current method of processing doppler signals?
The fast Fourier transform (FFT) OR Spectral analysis
What is the typical range of doppler shift found in diagnostic imaging examinations?
Between 20 Hz and 20 kHz
The phenomenon where high velocities appear in the opposite direction is called ______
Aliasing
The frequency at which aliasing occurs is called _______
Nyquist limit
The area of interrogation in a pulsed doppler exam is called _____
Sample volume
T or F. The higher the emitted frequency, the more likely a pulsed wave signal is to alias.
True
T or F. Shallower sample volumes result in more aliasing.
False
T or F. Only pulsed wave doppler exams have a sample volume.
True
An 8 MHz transducer with a pulse repetition of 5,000 Hz is imaging to a depth of 7 cm. What is the Nyquist frequency?
2.5 kHz or 2,500 Hz
An 8 MHz transducer with a pulse repetition 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?
3,500 Hz
T or F. A successful doppler exam cannot be performed on a severely anemic patient.
False
Which technique is used to perform spectral analysis on color doppler data?
Autocorrelation
Which technique is used to perform spectral analysis on pulsed doppler data?
Fast Fourier Transform (FFT)
Which of the following terms is synonymous with spectral broadening?
Turbulent flow
Which of the following is an advantage of a large packet size?
Increased doppler accuracy
Why are dedicated continuous wave doppler transducers so sensitive?
Absence of backing material
T or F. The lumen of a horizontal vessel evaluated with a color doppler, sector shaped image contains a single color.
False
