doppler final Flashcards
when color gain is set to an inappropriately high level, color appears throughout the color box. A term that describes this is called______________
color confetti
Multiple utrasound pulses that are used to accurately determine blood velocities are called ___________
ensemble
A wall filter is used to eliminate high frequency Doppler shifts from moving anatomy rather than from moving blood cells. TorF
False
The 3 basic forms of blood flow are:
pulsatile, phasic, and steady
The Reynolds number for turbulent flow is greater than 2,000. TorF
True
Which technique is used to perform spectral analysis on color Doppler data?
autocorrelation
Velocity mode distinguishes laminar flow from turbulent flow. TorF
False
What are the 2 things that are correct about pulsed Doppler transducers?
at least 1 crystal and lower sensitivity
The _____________ frequency is the highest Doppler frequency that can be measured without the appearance of aliasing
Nyquist
What is the most common error with Doppler ultrasound?
Aliasing
The Law of Conservation of Energy states that the pressure is lowest at _________
the stenosis
The phasic and steady flow are present in venous circulation. TorF
True
Simultaneous anatomic imaging and Doppler is called
duplex imaging
Doppler shift is inversely related to the frequency of the transmitted sound. TorF
False
When the blood cells are moving __________ to the sound beam, the entire velocity is measured.
parallel
Turbulent flow profiles may be seen _______ from a significant stenosis in a vessel.
downstream
Flow increases when either
a. pressure gradient increases and resistance decreases
b. resistance increases
c. pressure gradient decreases
a.
Assume that a doppler study is performed and the Doppler shift is 6kHz when the blood’s velocity is 2m/s. If the blood velocity slows to 1m/s. What will the Doppler shift be?
3kHz
_____________ is defined by a magnitude and a direction.
velocity
This process extracts the low Doppler frequency form the transducers carrier frequency.
demodulation
The lumen of a horizontal vessel evaluated with a color doppler, sector shaped image contains a single color. TorF
False
If a patient is supine what is the arterial pressure at the knee?
140mmHg
Tissue vibration associated with turbulence is called a
thrill
Transducer frequencies of ___________ Doppler shifts range are used since they are audible
20Hz-20,000Hz
Cosine 0 degrees is 1 indicating flow _____________ the transducer, whereas cosine 180 degrees is -1 indicating flow __________ from the transducer.
toward, away
All of the following occur during expiration except
a. venous flow in the legs increases
b. the diaphragm rises into the thoracic cavity
c. venous return to the heart decreases
d. abdominal pressure increases
d. abdominal pressure increases
What is the hydrostatic pressure of the waist if the person is standing?
50 mmHg
Blood moving from regions of higher energy to lower energy is called what
energy gradient
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent. TorF
False
Velocity mode color Doppler and variance mode color doppler will produce identical images when blood flow patterns are laminar. TorF
True
Absence of color on a color Doppler image always indicates a region of no blood flow. TorF
False
During a pulsed Doppler exam, aliasing is observed. Al of the following may eliminate aliasing except.
a. selection of another imaging view with a shallower sample volume
b. selection of another transducer with a lower frequency
c. selection of another imaging view that provides a greater pulse repetition period
d. use of a continuous wave system
C.
The highest Doppler frequency without the appearance of aliasing is called the ___________ and is equal to ________.
Nyquist limit, half of the emitted PRF
The higher the pulse repetition frequency of a doppler exam, the more likely aliasing is to occur. TorF
False
What happens to venous flow in the legs during inspiration?
decreases
The Reynolds number for laminar flow is less than
a. 1500
b. 1200
c. 1000
a 1500
__________ in a fluid system is called voltage. Similarly, _________ in a fluid system is called a current.
pressure, flow
What is the arterial pressure measured at the patients knee who is standing and the hydrostatic blood pressure is 140 mmHg?
c. 215mmHg (140+75)
During expiration, the diaphragm moves UP or DOWN
UP
Gravitational energy is a form of ____________ energy
stored
___________ energy loss in blood is determined by the hematocrit.
viscous
Parabolic flow is the velocity in the center of the lumen and gradually decreases to its minimum at the vessel wall. TorF
True
An advantage of power mode doppler is
unaffected by doppler angles
Ghosting artifact show up only on spectral doppler. TorF
False
Color Doppler will have crosstalk as an artifact. TorF
False
Wall filters are used to eliminate low frequency Doppler shifts from moving anatomy. TorF
True
What is the current method of processing Doppler signals that can distinguish laminar and turbulent flow?
FFT
Which of the following terms is synonymous with spectral broadening?
turbulent flow
Supine means that your are ____________
laying flat on your back
Stenosis will have increased velocity within the stenosis. TorF
True
