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157 Cards in this Set
- Front
- Back
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What is the reciprocal of centi? |
hecto (100) |
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True/False: Color-flow Doppler uses Fast Fourier Transform to assess velocities. |
False *color-flow doppler uses autocorrelation |
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True/False: Doppler effect is based on differences of signal amplitude. |
False *relative frequency is based on differences of signal amplitude |
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*Boards question What happens to the Nyquist limit as the depth of scan increases? |
decreases nyquist limit (frequency) = PRF/2 2(nyquist limit) = PRF (direct relationship) if depth of scan increases, PRF decreases. Therefore nyquist limit will decrease |
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True/False: When using color Doppler, the vessel will appear without color if the sound beam is exactly 60 degrees. |
False |
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What happens to the image if the speed of sound differs from the expected 1.54 km/s? |
the depth will be off
*image will shift higher if the speed is faster than the expected *image will shift lower if the speed is slower than the expected |
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What are the two things (questions) to remember when discussing artifacts? |
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True/False: The amount of Doppler Shift is always in MHz. |
False *kHz |
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What is -3 dB of 50 mW? |
25 mW *- 3dB is half * 3dB is double |
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What is 3 dB of 100 mW? |
200 mW *3dB is double *-3dB is half |
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What is 6 dB of 50 mW? |
200 mW
*3 dB is double *6 dB is doubled 2 times |
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What is the difference in a Doppler image when adjusting scale and Wall filter? |
they both eliminate signal (lower velocities)
*wall filter will not eliminate high velocities (aliasing), scale will |
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Wall filter eliminates signal based on ________________. |
frequency (velocity) |
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True/False: Wall filter does not eliminate aliasing (high frequencies). |
True |
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Where does all of the Spectral Doppler information come from? |
scan line and sample volume |
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What is the study of blood moving through the circulatory system called? |
hemodynamics |
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What are the three basic forms of blood flow? |
pulsatile phasic steady |
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True/False: Plug flow is proximal to the stenotic area. |
True |
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What are the two forms of Laminar flow? |
Plug flow Parabolic flow |
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___________ flow occurs when all of the layers and blood cells travel at the same velocity. |
Plug flow *form of laminar flow |
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____________ flow has a bullet-shaped profile. Velocity is highest in the center of the lumen, and gradually decreases to its minimum at the vessel wall. |
Parabolic flow *form of laminar flow |
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True/False: Laminar flow is silent flow. |
True |
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______________ flow is often associated with cardiovascular pathology and elevated blood velocities. |
Turbulent flow |
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Sound associated with turbulent flow is called? |
murmur or bruit |
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True/False: Tissue vibration associated with turbulence is called a thrill. |
True |
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Blood that moves from regions of higher energy to lower energy, is called? |
energy gradient *pressure, kinetic, and gravitational are forms of energy |
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Name the three forms of energy associated with blood flow. |
kinetic pressure gravitational |
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True/False: Pressure energy and gravitational energy are forms of stored or potential energy. |
True |
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True/False: Plug flow is often accelerated flow through large vessels. |
True |
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The _______________ velocity and _____________ pressure is located at the center of a stenotic area. |
highest velocity lowest pressure |
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True/False: Proximal to the stenotic area has accelerated flow. |
True |
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True/False: The pressure downstream from the stenosis is lower than the pressure upstream. |
True |
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True/False: The highest pressure is proximal (before) the stenotic area. |
True |
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Bernoulli's Principle explains that the _____________ blood velocity and ______________ pressure is at the center of the stenotic area. |
highest velocity lowest pressure |
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If the hydrostatic pressure of a patient is 0 mmHg, what position is the patient in? |
supine
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What is the hydrostatic pressure everywhere of a standing patient? |
it varies |
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During inspiration, thoracic pressure ____________, while abdominal pressure ____________. |
thoracic pressure decreases abdominal pressure increases |
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The apparent shift in frequency due to relative motion at an angle other than 90 degrees, is called? |
Doppler |
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True/False: Doppler shift is a frequency shift. |
True
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True/False: Spectral Doppler is always a graph. |
True |
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True/False: The sonographer can adjust the color box of the ultrasound machine. |
True
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The cosine of (0) is? |
one |
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The sine of (0) is? |
zero |
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What is the Doppler shift at an angle of 90 degrees? |
zero |
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True/False: the equation: f dop = 2 f V cos (theta)/C ...describes the frequency heard. |
False *describes the amount of Doppler shift *f dop represents Doppler shift *#2 in the equation represents down + back *f is operating freq of transducer *V is blood velocity *C represents propagation speed |
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True/False: If there is a velocity difference between the source and the observer, there is always a Doppler shift. |
True |
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True/False: Color Doppler slows down the frame rate. |
True |
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True/False: The wider the color box, the better the frame rate. |
False *wider color box, slower frame rate |
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True/False:
A longer (taller) color box does not slow down the frame rate. |
True |
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_______________ takes information (Doppler frequency) from the signal (transducer frequency). |
Demodulation |
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True/False: Doppler shifts are frequently in the kHz range (audible range). |
True *Doppler shift = reflected freq - transmit freq |
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True/False: When blood cells move toward the transducer, the Doppler shift is positive. |
True *the reflected frequency is higher than the transmitted frequency |
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True/False: The larger the velocity difference, the larger the Doppler shift. |
True |
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True/False: Wall filter eliminates signal based on frequency (velocity). |
True |
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True/False: Doppler is the difference between the transmitted and received frequencies (velocities). |
True
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True/False: We do use Doppler to obtain the blood's velocity. |
True |
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Does making the Doppler color box wider make the frame rate decrease? |
Yes |
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Does making the Doppler color box longer (taller) make the frame rate decrease? |
No *does not matter how deep the scan is in reference to color box because the packet size won't change |
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By just turning on the color Doppler, does it slow down the frame rate? |
Yes |
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When blood cells move away from the transducer it is a _____________ (+/-) shift. |
negative |
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If the transducer frequency doubles, but the velocity of blood is cut in half, what is the effect on the Doppler shift? |
unchanged f dop = 2 f V cos (theta)/C |
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True/False: Frequency has a direct relationship with velocity. |
True *frequency change = velocity change |
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Velocity has a(n) __________ relationship with Doppler shift. |
direct |
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Velocity has a(n) ______________ relationship with frequency. |
direct |
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Frequency has a(n) ______________ relationship with Doppler shift. |
direct |
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True/False: If objects are moving towards each other, they hear a higher frequency. |
True |
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What is the best angle for gray scale imaging? |
90 degrees *but then there is no Doppler (black) |
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Are any changes made to the transducer frequency going to affect the measured Doppler? |
No
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For the measured velocity, do we need to do anything for a changed transducer? |
No
*the machine will recognize the change and adapt for measurements
*"do not have to do math in your head if you make adjustments on the display" -marty |
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If the transducer frequency doubles, what happens to the amount of the Doppler shift? |
doubles |
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True/False:
Measured Doppler is not obvious to the sonographer. |
True |
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If the Doppler angle is 0 degrees, then the cosine is ____. |
1 |
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If the Doppler angle is 90 degrees, then the cosine is _____. |
0 *there is no Doppler info |
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If the Doppler angle is 180 degrees, then the cosine is ______. |
- 1 *180 degrees gives the largest magnitude (just goes in opposite direction) |
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Which Doppler angle gives a larger value? a) 60 degrees b) 90 degrees c) 180 degrees d) 150 degrees |
c) 180 degrees *even though it is negative 1, it is still a magnitude of 1 |
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What is a commonly used signal processing technique for bidirectional Doppler (distinguishes flow toward/away from transducer)? |
Phase quadrature (quadrature detection) *"works very well" -marty |
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For a dedicated CW Doppler, what is the Duty Factor? |
one *(100%) |
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_______________ wave Doppler has no backing material and has range ambiguity (location limitation).
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Continuous wave Doppler *is on all of the time *2 crystals (1 transmit/1receive) *no aliasing |
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Dedicated CW transducers do not have backing material, resulting in which of the following? a) undampened transmitted signal b) narrow bandwidth c) high quality factor d) higher sensitivity e) all of the above |
e) all of the above |
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With _____________ wave Doppler, all of the Spectral Doppler information comes from the sample volume. |
Pulsed wave Doppler *has aliasing |
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The ability to select the exact location where velocities are measured in Pulsed wave Doppler, is called? |
range resolution *aka range specificity or freedom from range ambiguity artifact |
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True/False: All of the Spectral Doppler information for Continuous wave Doppler comes from the 'overlap' region. |
True |
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Pulsed wave Doppler has which of the following? a) backing material b) low quality factor c) lower sensitivity d) wide bandwidth pulses e) all of the above |
e) all of the above |
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The Nyquist limit is equal to? |
PRF/2 |
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True/False: The Nyquist limit is equal to one-half the PRF. |
True |
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If the PRF is 4 kHz, what is the Nyquist limit? |
2 kHz *nyquist limit = PRF/2 |
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The ___________ __________ is the highest velocities that can be accurately measured. |
Nyquist limit |
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True/False:
The Nyquist limit gives us the highest blood velocities we can accurately measure. |
True |
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True/False: The PRF (sampling rate) is controlled by depth. |
True *cannot sample as often at greater depths, more likely to have aliasing |
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True/False: If you sample a signal often enough, you can reproduce it. |
True |
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True/False: If blood velocities are too high, the amount of Doppler shift will be great. |
True |
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What are ways to avoid aliasing? (5) |
adjust scale to maximum new view with shallower sample volume lower frequency transducer baseline shift use CW Doppler |
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True/False: Gray-scale tells you how many blood cells are at a certain velocity in Doppler. |
True |
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True/False:
Color-flow Doppler comes from a larger region, and to use Color-flow, a packet size or an ensemble is needed. |
True |
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Multiple sound pulses along the exact same scan line, are called? |
Doppler packets *normally 8 pulses *the more sound pulses in the packet, the longer is takes |
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What gives the ability to sample a much larger volume?
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Doppler packets *uses color, does not include PW or CW *uses frame rate |
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_____________ Doppler has increased sensitivity to low flow, and is unaffected by Doppler angles, but gives no measurement of velocity or direction of blood flow. |
Power Doppler
*no aliasing *very sensitive to the slightest motion |
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True/False:
Anytime any type of color Doppler is used (color-flow, power) there will be a lower frame rate because of the Doppler packet size. |
True |
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Name the methods of Spectral Analysis. |
Fast Fourier Transform FFT (PW + CW) Autocorrelation (color-flow, power) |
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Which spectral analysis method will give you average values? |
Autocorrelation *color-flow + power |
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Which spectral analysis method will give you peak values? |
Fast Fourier Transform FFT *PW + CW |
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Which spectral analysis method is used for all types of color Doppler (color-flow, power)? |
Autocorrelation |
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Which spectral analysis method is used for spectral Doppler (PW, CW)? |
Fast Fourier Transform FFT |
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True/False: The speed of sound in soft tissue is 154,000 cm/s. |
True *1,540 m/s |
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True/False: The speed of sound in soft tissue is 1.54 km/s. |
True *1,540 m/s |
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True/False:
Since the cosine of 90 degrees is zero, no Doppler shift is created or measured, and no color flow appears. |
True
*90 degrees to a vessel will not get Doppler |
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True/False: Color will never appear in a vessel when the directions of flow and sound are perpendicular. |
True |
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True/False: In order to reduce the 'confetti' look or color outside of a vessel when using color Doppler, you should turn the color gain up. |
False *turn the color gain (Doppler gain) down note: if turned down too much, no color is seen |
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True/False: To remove color outside of a vessel, reduce the color gain. |
True *decrease color gain |
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True/False:
If 'wrap-around' is occurying during spectral Doppler, reduce the spectral Doppler gain. |
True |
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True/False:
To eliminate color-flow outside of a vessel, increase the Wall filter. |
True
*eliminates signal based on frequency (velocity) |
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True/False:
If the colors that touch each other go through the map's middle (black) of the color map, flow reversal is present. |
True
*ie. red and yellow next to each other |
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True/False: If the colors that touch each other on a color map go around the outside of the map, aliasing is present. |
True
*ie. blue and yellow next to each other |
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Wall filter eliminates signal based on _________________. |
frequency (velocity) |
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True/False: Wall filter eliminates aliasing. |
False *wall filter does not eliminate aliasing |
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True/False: The most effective way to eliminate aliasing on a color-flow image is to increase the velocity scale. |
True |
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What are the two questions that should be asked when refering to artifact? |
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Which assumption is violated with reverberation artifact? |
Assumption #2: sound travels directly to a reflector and back |
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True/False: Reverberation artifact causes extra reflectors and hinders the down and back activity of a sound beam. |
True |
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True/False: Comet Tail is a version of Reverberation artifact. |
True |
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Which assumption is violated by Shadow artifact? |
Assumption #6: the intensity of a reflection is related to the tissue creating the reflection |
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True/False: Shadow artifact travels through a high attenuating tissue/structure, therefore no sound can get below it. |
True *shadow = lack of echoes |
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Which assumption does Enhancement artifact violate? |
Assumption #6: the intensity of a reflection is related to the characteristics of the tissue *enhancement = brightens area |
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Which assumption(s) does Mirror image artifact violate? |
Assumption #1: sound travels in a straight line Assumption #2: sound travels directly to a reflector and back to the transducer |
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True/False: The Mirror image artifact is located deeper than the real structure. |
True *mirror image creates an extra image but it is too deep |
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True/False: Mirror image artifact has an extra reflector. |
True |
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True/False: For Speed Error artifact, if the sound is too fast the image will be too high. If the sound is too slow the image will be too low. |
True *speed error has no extra images |
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What are the two methods to eliminate lobes? |
subdicing apodization |
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True/False: Refraction causes an extra image that is laterally displaced. |
True |
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Which assumption does Refraction artifact violate? |
Assumption #1: sound travels in a straight line |
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True/False: Mirror image artifact creates an extra image that is too deep (axially displaced). |
True *axial = parallel to the beams main axis |
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True/False: Lateral Resolution, Axial Resolution, Spatial Resolution, and Temporal Resolution are all artifacts. |
True |
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What is the most common artifact? |
per boards: Shadow artifact in actuality: Speckle artifact |
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True/False: Speckle artifact gives imaged tissue some texture. It is a combination of constructive and destructive interference. |
True |
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What is the sine of 0 degrees? |
zero |
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What is the cosine of 0 degrees? |
one |
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True/False: CW Doppler produces no anatomical image. |
True *because it cannot identify specific depth |
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True/False:
As the depth of scan increases, the PRF decreases, and aliasing increases. |
True
*depth and aliasing have a direct relationship
*PRF has an inverse relationship w/ depth and aliasing
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True/False: If the depth of scan increases, the PRP increases. |
True |
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True/False: Period and frequency always have an inverse relationship. |
True |
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True/False: Aliasing is based on sampling an area often enough to accurately reproduce the image (signal). |
True |
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True/False: If you decrease the PRF, you are sampling less often, and are more likely to have aliasing. |
True |
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True/False:
When using color Doppler, the vessel will appear without color if the sound beam angle is at exactly 90 degrees. |
True |
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What is the cosine of 90 degrees? |
zero |
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True/False:
The Doppler effect is based on differences of signal amplitudes. |
False
*Doppler effect is based on differences of frequency |
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True/False: Doppler moving away from the transducer has lower frequency. |
True |
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True/False:
The blood velocity in a vessel is zero if there is no color (black) in the area. |
False
* could be due to the angle, settings, or there could be blockage
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What is the cosine of 180 degrees? |
- 1 |
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True/False: Color Doppler uses autocorrelation to separate out velocities. |
True |
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True/False: If an artifact appears anywhere on an image, the entire image is useless. |
False |
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Which artifact puts multiple, evenly spaced reflectors on an image? |
reverberation |
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20 dB is an increase of ________. |
100 |
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A decrease in 10,000 times is how many decibels? |
- 40 dB |
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True/False: Doppler phantom assesses the characteristics of M-Mode. |
False *it assesses the characteristics of Doppler |
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True/False: The tissue equivalent phantom has attenuation properties. |
True |
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What does the gel help the sonographer do? |
scan superficially *by eliminating the dead zone |
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Can a single crystal transmit and receive at the same time? |
No |
