Physics tests Flashcards
supine means that you are
Laying flat on your back
True or False
Stenosis will have increased velocity within the stenosis
True
Tissue vibration associated with turbulence is called a
Thrill
Pressure energy is a form of _____________ energy
Potential
Turbulent flow profiles may be seen __________ from a significant stenosis in a vessel
Downstream
True or False
Plug flow is the velocity in the center of the lumen and gradually decreases to its minimum at the vessel wall
False
The three basic forms of blood flow are
Pulsatile, phasic and steady
If a patient is supine, what is the arterial pressure at the knee?
140 mmHg
During inspiration, the diaphragm moves
Down
What happens to venous flow in the legs during inspiration?
Decreases
The law of conservation of energy states that the pressure is lowest at
the stenosis
True or False
Viscosity describes the energy flow when heat is converted as one object rubs against another
False
as blood flows through the circulation, energy is lost in what 3 ways
viscous, frictional, inertial
True or False
The Reynolds number for turbulent flow is greater than 2,000
True
What is the hydrostatic pressure at the waist if the person is standing?
50 mmHg
What is the arterial pressure measured at this patients knee – the hydrostatic pressure is 140mmHg?
215mmHg
Blood moving from regions of higher energy to lower energy is called
Energy gradient
True or False
Phasic and steady flow are present in venous circulation
True
The Reynolds number for laminar flow is less than
1500
Flow increases when either
pressure gradient increases and resistance decreases
What are the hydrostatic pressures while standing upright in a patient with a blood pressure of 140mmHg
ankle 100 knee 75 waist 50 Mid chest 0 top of head -30
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 ultrasound pulses that are used to accurately determine blood velocities are called
Ensemble
True or False
a wall filter is used to eliminate high frequency Doppler shifts from moving anatomy rather than from moving blood cells
False
Which technique is used to perform spectral analysis on color Doppler data?
Autocorrelation
True or False
velocity mode distinguishes laminar flow from turbulent flow
False
What re the 2 things that are correct about pulsed Doppler transducers?
at least 1 crystal and lower sensitivity
The _______ frequency is the highest Doppler frequency than can be measured without the appearance of aliasing
Nyquist limit
What is the most common error with Doppler ultrasound?
Aliasing
Simultaneous anatomic imaging and Doppler is called
Duplex imaging
True or False
Doppler shift is inversely related to the frequency of the transmitted sound
False
When the bloos cells are moving _____ to the sound beam, the entire velocity is measured
Parallel
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 from the transducer’s carrier frequency
Demodulation
True or false
The lumen of a horizontal vessel evaluated with a color Doppler, Sector shaped image contains a single color
False
Transducer frequencies of _________ Doppler shifts range are used since they are audible
20Hz-20000Hz
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
True or False
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent
False
True or False
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are laminar
True
True or False
Absence of color on a color Doppler image always indicates a region of no blood flow
False
During a pulsed Doppler exam, aliasing is observed. All 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. selection of another imaging view that provides a greater pulse repetition period
The highest Doppler frequency without the appearance of aliasing is called the ________ and is equal to ______
Nyquist limit, half the emitted PRF
True or False
The higher the pulse repetition frequency of a Doppler exam, the more likely aliasing is to occur
False
What happens to venous flow in the legs during inspiration?
Decreases