Doppler Instrumentation and Hemodynamics Flashcards
What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4 cm? A. 40 cm/s B. 200 cm/s C. 2.5 m/s D. 4 m/s E. None of the above
E. None of the above
You will see aliasing of the Doppler spectrum whenever the frequency shift exceeds:
A. Twice the pulse repetition frequency
B. Three times the pulse repetition frequency
C. One-third the pulse repetition frequency
D. One- half the pulse repetition frequency
E. One-fourth the pulse repetition frequency
D. One- half the pulse repetition frequency
You obtained this Color Doppler image while performing hepatic sonography. There is no color signal detected within the portal vein. What can you do to improve sensitivity to slow flow? Pg 100 A. Increases wall filter B. Decrease packet size C. Decrease color gain D. Decrease pulse repetition frequency
D. Decrease pulse repetition frequency
The packet size in Color Doppler refers to the number of:
A. Pulses per sec
B. Sample volumes per scan line
C. Scan lines per unit area
D. Pulse/listen cycles per acoustic scan line
D. Pulse/listen cycles per acoustic scan line
Which of the following is present in this Doppler spectral waveform? Pg 101 A. Spectral broadening B. Narrow velocity range C. Aliasing D. Mirror image
A. Spectral broadening
While performing a Doppler study, you underestimated the measurement of the Doppler angle of incidence. What error will result from this mistake?
A. The frequency shift will be underestimated
B. No Doppler frequency shift will be detected
C. Mirror imaging of the Doppler spectrum will occur
D. The velocity estimation will be inaccurate
D. The velocity estimation will be inaccurate
Which transducer will detect the largest Doppler frequency shift? Pg 102 A B C D E
A
Which transducer will NOT detect Doppler frequency shift? Pg 102 A B C D E
E
Which transducer would demonstrate a waveform ABOVE the zero baseline? Pg 102 A B C D E. All except for E
E. All except for E
A commonly used process for determining direction in a Doppler instrument is: A. Zero- crossing detection B. Autocorrelation C. Phase quadrate detection D. Range gating
C. Phase quadrate detection
What method is used to steer the color beam with a linear array transducer? A. Mechanical B. Electronic time delays C. Electronic voltage variation D. Apodization
B. Electronic time delays
When color doppler is activated , in order to maintain frame rate, what may be reduced in the underlying B-mode image? A. The number of focal zones B. The scan line density C. The frame averaging D. A and B
D. A and B
What Doppler technique does NOT provide range resolution? A. Color Doppler B. Power Doppler C. Pulsed-wave Doppler D. Continuous wave Doppler
D. Continuous wave Doppler
You have obtained a color Doppler image of the common carotid artery. If the received ultrasound frequency is greater than transmitted ultrasound frequency, which of the following would be correct?
A. Color encoding red, negative Doppler shift
B. Color encoding blue, negative Doppler shift
C. Color encoding red, positive Doppler shift
D. Color encoding blue, positive Doppler shift
C. Color encoding red, positive Doppler shift
Aliasing is a potential problem in PW Doppler because of:
A. The use of high pulse repetition frequencies
B. The Doppler signal being sampled rather than recorded continuously
C. Dynamic focusing
D. The motion of the interface perpendicular to ultrasound wave propagation
B. The Doppler signal being sampled rather than recorded continuously
What does the Doppler signal spectral display depict?
A. Relative signal power at each frequency in the Doppler signal
B. Depth to each vessel
C. Volume flow rate
D. Transmit frequency
A. Relative signal power at each frequency in the Doppler signal
Increasing the wall filter during Doppler sampling will:
A. Increase visibility of low velocity signals
B. Increase spectral broadening
C. Decrease bandwidth
D. Reduce display of low frequency
D. Reduce display of low frequency
What would be the most likely result from increasing the transmit frequency of the Color Doppler ?
A. Improved sensitivity to slow flow
B. Improved penetration for imaging flow in deep tissues
C. Reduced flash artifact obscuring small vessel flow
D. Reduced Color Doppler aliasing
A. Improved sensitivity to slow flow
What would be the most likely result from lowering the color threshold?
A. Increased visibility of small vessel flow in parenchymal organ
B. Decreased flash artifact
C. Increased color writing on the vessel or cardiac wall
D. Increased frame rate
C. Increased color writing on the vessel or cardiac wall
What method is most commonly used to perform spectral analysis for pulsed Doppler? A. Zero-crossing detection B. Fourier analysis C. Reynolds number D. Cross correlation
B. Fourier analysis
During Doppler interrogation of the carotid artery, you detect spectral mirroring. Which of the following is a common cause of this artifact?
A. Doppler angle of interrogation near 90*
B. Doppler angle of interrogation near 0*
C. Wall filter set too high
D. PRF set too low
A. Doppler angle of interrogation near 90*
This Doppler waveform can be most accurately described as exhibiting: Pg 105 A. Aliasing B. Spectral broadening C. Mirror-image artifact D. Bidirectional flow
A. Aliasing
What system control should be adjusted to optimize this waveform? Pg 105 A. Wall filter B. Packet size C. Gain D. Pulse repetition frequency
D. Pulse repetition frequency
What Doppler control should be adjusted to optimize this Doppler spectral waveform? A. Wall filter B. Packet size C. Gain D. Pulse repetition frequency
C. Gain
The Doppler frequency shift is defined as:
A. The difference between the Doppler frequency and the imaging frequency
B. The difference between the transmitted and received signals
C. The time between the transmitted and received pulses
D. The rate at which the transducer emits pulses
B. The difference between the transmitted and received signals
According to the Doppler equation , which of the following is NOT true?
A. Increasing Doppler frequency will increase the frequency shift
B. Increasing the Doppler interrogation angle will increase the frequency shift
C. Decreasing the reflector speed will decrease the frequency shift
D. No frequency shift is detected when the Doppler beam strikes the reflector with perpendicular incidence
B. Increasing the Doppler interrogation angle will increase the frequency shift
The Nyquist limit describes ________:
A. penetration limit of pulsed-wave Doppler
B. Transmit time of pulsed-wave Doppler
C. Sampling frequency needed for detecting the Doppler signal unambiguously
D. Sampling method used for continuous-wave Doppler
C. Sampling frequency needed for detecting the Doppler signal unambiguously
What information does the z-axis (brightness) on the Doppler spectrum provide? A. Velocity B. Velocity range C. Bandwidth D. Amplitude
D. Amplitude
A waveform from the internal carotid artery obtained at a Doppler angle of 45* shows aliasing. Which of the following choices will help you unwrap this waveform?
A. Decrease the angle of incidence
B. Decrease the high pass filter
C. Raise the zero baseline
D. Increase the pulse repetition frequency
D. Increase the pulse repetition frequency
While performing a color Doppler exam in the abdomen you have adjusted several system controls and notice that the frame rate has decreased . Which of the following adjustments can you make to improve the color frame rate?
A. Increase the packet size
B. Decrease the pulse repetition frequency
C. Decrease the color box width
D. Increase the scan line density
C. Decrease the color box width
You are performing a carotid duplex examination with the following parameters: 5MHz Doppler frequency, 6 kHz PRF, 4 cm depth, and 1.5 mm sample volume length. What is the aliasing frequency? A. 5 MHz B. 6kHz C. 12kHz D. 1.5MHz E. 3kHz
E. 3kHz
The rapid technique used in most color Doppler systems to obtain the mean Doppler frequency shift is : A. Fast Fourier transform B. Phase quadrate C. Autocorrelation D. Zero-crossing detector
C. Autocorrelation
What information is colorized in an image using Power Doppler? A. Frequency shift B. Flow velocity C. Doppler signal amplitude D. Frequency bandwidth
C. Doppler signal amplitude
In the following waveform, the end-diastolic flow velocity cannot be measured. What control adjustment should be performed to obtain this measurement?pg108 A. Increase pulse repetition frequency B. Decrease the angle of incidence C. Lower the zero baseline D. Increase the Doppler gain E. Lower the wall filter
E. Lower the wall filter
You have encountered spectral broadening of the internal carotid artery waveform. This most likely indicates: A. Slow heart rate B. Tachycardia C. Accelerated flow D. Turbulent flow
D. Turbulent flow
What flow characteristic is depicted in this illustration? A. Turbulent flow B. Blunt flow profile C. Flat flow profile D. Stenotic flow profile E. Parabolic flow profile
E. Parabolic flow profile
What term describes the number of pulses that are used to determine the velocity along a color line of sight? A. Color gate B. Packet size C. Pulse repetition frequency D. Pulse duration
B. Packet size
What display method will help you demonstrate flow turbulence with color Doppler? A. Autocorrelation B. Variance C. Fast Fourier analysis D. Zero-crossing detection
B. Variance
What term would describe a Doppler waveform obtained at location "C: in this depiction of an arterial stenosis? pg 109 A. Parabolic flow profile B. Laminar flow profile C. Plug flow profile D. Spectral broadening flow profile
D. Spectral broadening flow profile
What parameter describes the axial length of the sampling volume for a color pixel? A. Color sample gate B. Packet size C. Pulse repetition frequency D. Pulse repetition period
A. Color sample gate
What type of Doppler device uses two elements , one to receive and one to transmit? A. Power Doppler B. Color Doppler C. Continuous-wave Doppler D. Pulsed -wave Doppler E. All of the above
C. Continuous-wave Doppler
Spectral analysdis is used to :
A. Determine the distrubution and magnitude of frequency shifts in the reflected Doppler signal
B. Eliminate aliasing from the reflected signal
C. Color-encode the Doppler frequenct shift
D. Eliminate the low-frequency shifts from the display
A. Determine the distrubution and magnitude of frequency shifts in the reflected Doppler signal
Color flash artifact is obscuring the anatomy of interest in an exam of the abdominal aorta. What can you do to reduce impact of the flash?
A. Increase the color gain
B. Decrease the pulse repetition frequency
C. Increase the wall filter
D. Increase the packet size
C. Increase the wall filter
While evaluating the liver vasculature with color doppler, you are unable to obtain signlas from the deeper vessels. What should you do to enhance your ability to demosntrate deep flow?
A. Decrease the packet size
B. Increase the scan line density
C. Increase the wall filter
D. Increase the pulse repetition frequency
E. Decrease the ultrasound frequency
E. Decrease the ultrasound frequency
Loss of fluid energy through inertia:
A. Is greatest during steady flow through a rigid tube of constant caliber
B. Is best described by Poiseuille’s law
C. Is greatest in a tortuous vessel with multiple obstructions
D. Accounts for less energy loss than viscous losses
C. Is greatest in a tortuous vessel with multiple obstructions
Which of the following statements about turbulent flow is NOT true?
A. It can be predicted by the Reynolds number
B. It is responsible for murmurs,bruits, and thrills
C. It causes an increase in pressure downstream
D. It occurs wjere there are abrupt variations in vessel diameter
C. It causes an increase in pressure downstream
Which of the following statements most correctly describes the occurrence of diastolic flow reversal in the arterial system ?
A. It is always an abnormal finding
B. It is seen in and proximal to high-resistance vessels
C. It is most commonly observed in vessels that supply low-resistance beds
D. It can be enhanced by body heating
B. It is seen in and proximal to high-resistance vessels
You measured an area reduction of 90% in the artery shown in this image pg 111. This is equeal to a diameter reduction of: A. 25% B. 30% C. 50% D. 75%
D. 75%
The Doppler waveform you have obtained from a collateral channel shows high resistance compared to the contralateral normal artery. This increased resistance may be attributed to:
A. Decreased tube diameter
B. Increased vessel length
C. Decreased resistance in the vascular bed
D. All of the above
E. A and B
E. A and B
After a short walking exercise, the venous pressure at the ankle of a standing normal subject:
A. Is greater than the standing ankle pressure at rest
B. Is lower than the standing ankle pressure at rest
C. Is the same as standing ankle pressure at rest
D. It is not affected by chronic venous insufficiently
B. Is lower than the standing ankle pressure at rest
Your patient has edema involving the right lower extremity. This may be caused by: A. Increased intravenous pressure B. Decreased venous hypertension C. Decreased venous hypervolemia D. Increased venous hypovolemia
A. Increased intravenous pressure
This waveform was obtained from the center flow channel within the common carotid artery. What term best describes this flow state? pg 112 A. Laminar flow B. Turbulent flow C. Reynolds flow D. High-resistance flow
A. Laminar flow
You are examining a pt with retrograde flow as demonstrated in this image. pg 112 What causes the flow to reverse its normal flow direction (arrow)?
A. An increase in pressure due to stenosis in a distal artery
B. A pressure drop due to a stenosis in a proximal artery
C. Loss of energy due to poststenotic turbulence
D. A decrease in volume flow due to stenosis in a distal lesion
B. A pressure drop due to a stenosis in a proximal artery
In this image of an arterial stenosis, the waveform indicates poststenotic turbulence. What term describes the point at which flow becomes turbulent? pg113 A. Poiseuille's law B. Bernoulli's equation C. Starling's law D. Reynolds number
D. Reynolds number
What conditions below are most likely to result in turbulent flow?
A. 5mm vessel with 300 cm/s flow velocity
B. 2mm vessel with 300 cm/s flow velocity
C. 2mm vessel with 30 cm/s flow velocity
D. 1mm vessel with 30 cm/s flow velocity
A. 5mm vessel with 300 cm/s flow velocity
What is the maximum velocity limit fort 3 MHz CW Doppler unit operating at a depth of 4cm? A. 40 cm/s B. 200 cm/s C. 2.5 m/s D. 4 m/s E. None of the above
E. None of the above
These images show flow within the sac of pseudoaneurysm. Image A shows more color fill than image B. What color control was changed to make image A look like image B? pg 114 A. Gain B. Threshold C. Transmit frequency D. PRF
D. PRF
Which of the following statements about formation of the color Doppler image is TRUE?
A. The color and B-mode images are generally derived from the same pulse
B. The color image is superimposed on the existing B-mode image.
C. The color and B-mode images are generally formed using the same frequency sound wave
D. The B-mode image is usually obtained at a lower frequency than the color image
B. The color image is superimposed on the existing B-mode image.
Which physics concept best explains why Doppler signal strength would be greater with a 6.3MHz transducer than with a 5.0 MHz transducer? pg115 A. Reynolds number B. Poiseuille's law C. Bernoulli effect D. Rayleigh scattering
D. Rayleigh scattering
What is the source of the bright echoes indicated by the arrow in this Doppler waveform? pg115 A. Spectral broadening B. Bruit C. Aliasing D. Mirror imaging
B. Bruit
What error will occur if the angle correct cursor is NOT adjusted parallel to the vessel wall?
A. The frequency shift will be underestimated
B. No Doppler frequency shift will be detected
C. Mirror imaging of the Doppler spectrum will occur
D. The velocity estimation will be inaccurate
D. The velocity estimation will be inaccurate
These two images show a pseudoaneurysmal sac. In image A, the gray-scale echoes within the flow are visible and the color does not fill the sac. What control was optimized in image B to allow the color to write over the gray-scale echoes?Pg 116 A. PRF B. Wall filter C. Gain D. Packet size E. Threshold(priority)
D. The velocity estimation will be inaccurate
The arrow in this image points to flow below the zero baseline. These echoes represent: Pg 117
A. Retrograde flow due to poststenotic turbulence
B. Aliasing
C. Mirror Imaging
D. Incorrect setting of Doppler gain
A. Retrograde flow due to poststenotic turbulence
Which of the following actions would decrease color Doppler frame rate? A. Decreasing frequency B. Increasing line density C. Decreasing packet size D. Decreasing color box size
B. Increasing line density
When color Doppler is active, how many pulses per scan line are typically used to create the underlying B-mode image? A. 1-2 B. 3-4 C. 5-6 D. 7-8
A. 1-2
What is the result of increasing the wall filter during Doppler sampling
A. Increased visibility of low-velocitiy signals
B. Increased spectral broadening
C. Decreased bandwidth
D. Reduced display of low-frequency Doppler signals
D. Reduced display of low-frequency Doppler signals
You have increased the packet size while using color Doppler to evaluate flow. What negative result will occur from this action? A. Decreased penetration B. Decreased flow sensitivity C. Decreased frame rate D. Increased variance
C. Decreased frame rate
What positive result will occur from decreasing frame rate? A. Improved signal-to-noise ratio B. Reduced aliasing C. Improved axial resolution D. Improved lateral resolution
A. Improved signal-to-noise ratio
What system control on Doppler adjusts the PRF?? A. Dynamic range B. Packet size C. Ensemble length D. Gain E. Spectral velocity scale
E. Spectral velocity scale
This image shows the color significantly overwriting the vessel wall. Which of the following provides the best explanation for this?
Pg 119
A. The color Doppler threshold is set too low
B. The color Doppler scale is set too low
C. Axial resolution is lower with color Doppler compared to B-mode
D. Color Doppler uses a higher frequency transmitted pulse than B-mode
C. Axial resolution is lower with color Doppler compared to B-mode
Which of the following could be used to increase the color frame rate for a cardiac image? A. Decrease the image width B. Decrease the packet size C. Decrease the line density D. A and B E. All of the above
E. All of the above
If you increase the Doppler transmit frequecy, which of the following will result?
A. The velocity will increase
B. The Doppler frequency shift will increase
C. The penetration will increase
D. The frame rate will increase
B. The Doppler frequency shift will increase
Which control optimization should you make to improve color Doppler sensitivity to slow flow?
A. Lower the packet size
B. Lower the transmitted ultrasound frequency
C. Raise the PRF
D. Lower the wall filter setting
D. Lower the wall filter setting
This Doppler waveform is displayed below the zero baseline. Given the settings displayed in this image. Which of the following is true? pg 120 #524
A. The direction of flow is toward the beam
B. The Doppler shift is negative
C. The flow is antegrade
D. The system has malfunctioned
A. The direction of flow is toward the beam
What statement is correct regarding the comparison of these two waveforms? PG 120 #525
a. Waveform A shows a delayed systolic upstroke compared to B
B. Waveform A shows decreased spectral broadening compared to B
C. Waveform A indicates the presence of proximal disease and waveform B is normal
D. Waveform A indicates a low-resistance state compared to waveform B
D. Waveform A indicates a low-resistance state compared to waveform B
In this image, the red color indicated by the arrow represents Pg 121: A. Flow toward the ultrasound transducer B. Flow away from the sound beam C. Turbulent flow D. Aliased flow
A. Flow toward the ultrasound transducer
In this image, the color green represents: pg 121 #527 A. Aliasing B. Variance C. Negative Doppler shift D. Laminar flow
B. Variance
In this image, the Doppler frequency shift exhibits: A. Aliasing B. Spectral broadening C. Narrow bandwidth D. Mirroring E. All of the above
B. Spectral broadening
What aspect of the Doppler spectrum is color-encoded with color Doppler? A. Amplitude B. Frequency shift C. Power D. Velocity
B. Frequency shift
Which of the following occurs when you lower the pulse repetition frequency? A. The wall filter is increased B. The frame rate is increased C. The line density is increased D. The Nyquist limit is decreased
D. The Nyquist limit is decreased
In this color map, what color represents the highest positive Doppler shift? pg 123 A. Dark red B. Dark blue C. Black D. Yellow/ Orange E. Cyan
D. Yellow/ Orange
What color represents flow at 90* at the sound beam? A. Dark red B. Dark blue C. Black D. Yellow/ Orange E. Cyan
C. Black
Which color would represent an aliased Doppler signal from flow coursing away from the transducer? A. Dark red B. Dark blue C. Black D. Yellow/ Orange E. Cyan
D. Yellow/ Orange
The velocity scale on this color map is 17 cm/s. If the flow direction is at zero degrees to the sound beam axis , the colors on either end of the bar would represent: A. A peak velocity of 17 cm/s B. An average velocity of 17 cm/s C. A peak velocity of 34 cm/s D. A peak velocity above 17 cm/s
B. An average velocity of 17 cm/s
Which answer provides the best explanation for the reason that the frame rate decreases when Color Doppler is activated?
A. The color Doppler pulse length is longer
B. There are more focal zones when color is activate
C. The system memory resources are challenged
D. More pulses are fired on each line of sight
D. More pulses are fired on each line of sight
The control that sets the gray-scale brightness at which color will be displayed instead of gray-scale at a pixel location is termed: A. Priority B. Line Density C. Persistence D. Ensemble length E. Scale
A. Priority
Regarding this image, the angle of the beam to the vessel is approximately: A. 0* B. 60* C. 90* D. 45* E. 360*
C. 90*
What two controls affect the spatial resolution of this color image? A. Line density and ensemble length B. Ensemble length and priority C. Frequency and line density D. Frequency and ensemble length
C. Frequency and line density
According to the Doppler equation, for any given velocity , the frequency shift will increase by increasing the: A. Doppler angle B. Transmit frequency C. Pulse length D. Pulse repetition frequency
B. Transmit frequency
The most numerous cells in the blood are the: A. Erythrocytes B. Leukocytes C. Platelets D. Plasma E. Lymphocytes
A. Erythrocytes
The Reynolds number increases with increasing: A. Flow speed B. Vessel diameter C. Blood Density D. Blood flow velocity E. All of the above
E. All of the above
Which term refers to the fact that the volumetric flow rate must be the same proximal , at, and distal to a stenosis? A. Continuity rule B. Reynolds number C. Poiseuille's law D. The Bernoulli effect E. The Nyquist limit
A. Continuity rule
Decreased pressure occurs in areas of high flow speeds. This is known as: A. Continuity rule B. Reynolds number C. Poiseuille's law D. The Bernoulli effect E. The Nyquist limit
D. The Bernoulli effect
The Doppler frequency shift is the difference between the:
A. Transmitted frequency and the pulse repetition frequency
B. Received frequency and the pulse repetition frequency
C. Received frequency and the transmitted frequency
D. Frequency bandwidth and the pulse repetition frequency
C. Received frequency and the transmitted frequency
What Reynolds number would indicate turbulent flow? A. 200 B. 300 C. 2000 D. 3000 E. C and D
E. C and D
Parabolic flow is most likely to occur: A. Distal to a stenosis B. In small veins C. In laminar flow states D. In disturbed flow
C. In laminar flow states
A flow condition in which parallel streamlines of flow are present within a tube is termed: A. Parabolic flow B. Laminar flow C. Aliased flow D. Disturbed flow
B. Laminar flow
According to Poiseuille's equation, what will happen to flow if pressure difference increases? A. Flow rate will increase B. Flow will stagnate C. Flow will become pulsatile D. Flow velocity will decrease
A. Flow rate will increase
If you increased the transmit frequency during a Doppler exam, what would be the expected result
A. Penetration would increase
B. Aliasing would be reduced
C. Flow velocity would increase
D. Doppler frequency shift would increase
E. All of the above
D. Doppler frequency shift would increase
If you increased the Doppler angle during an exam, what would be the expected result
A. Doppler frequency shift would decrease
B. Aliasing would be increased
C. Flow velocity would increase
D. Sound velocity would increase
A. Doppler frequency shift would decrease
If you make a mistake in the measurement of the Doppler angle, the error in velocity estimation will be greatest at which Doppler angle? A. 0* B. 30* C. 45* D. 60* E. 70*
E. 70*
Which of the following best describes the Doppler frequency shift when you encounter high velocities within a vessel? A. Amplitude is increased B. Power is increased C. Frequency shift is increased D. Bandwidth is decreased E. All of the above
C. Frequency shift is increased
Which best describes the cardiac output?
A. Volume of blood pumped by the heart per minute
B. Volume of blood in a vertical column
C. Quantity of blood moving through a vessel per unit of time
D. Maximum flow velocity within the vessel lumen
E. Hydrostatic pressure per minute
A. Volume of blood pumped by the heart per minute
Volume flow is determined by multiplying the cross-sectional area of the vessel with: A. Volume flow rate B. Mean velocity C. Peak velocity D. Minimum velocity
B. Mean velocity
The terms ensemble length and dwell time are synonymous with: A. Persistence B. Packet size C. Pulse repetition frequency D. Color threshold E. Autocorrelation
B. Packet size
The layer of the vessel wall that is a single layer of cells backed by a thin layer of elastin and collagen fibers is the: A. Adventitia B. Media C. intima D. Internal elastic lamina E. External elastic lamina
C. intima
The layer of the vessel wall that contains smooth muscle fibers is the: A. Adventitia B. Media C. intima D. Internal elastic lamina E. External elastic lamina
B. Media
At low velocities, the red blood cells adhere to one another forming multicellular clumps. This is termed: A. Rayleigh scattering B. Rouleau formation C. Huygen's principle D. Newtonian fluid E. Parabolic flow
B. Rouleau formation
The prescence of the systolic spectral window of the Doppler waveform is affected by: A. Sample volume size B. Turbulent flow C. Doppler gain D. Position of the Doppler sample volume E. All of the above
E. All of the above
You are most likely to see a color bruit in which of the following cases?
A. Trickle flow within a small residual lumen
B. Damped flow proximal to high-grade stenosis
C. Chronic vessel occlusion
D. Turbulent glow distal to a high-grade stenosis
D. Turbulent glow distal to a high-grade stenosis
The Frank-Starling mechanism helps to explain that when an arrythmia is present, the peak systolic velocity following a heart cycle with a longer time interval \_\_\_\_\_\_\_\_\_\_\_\_ one with a shorter time interval A. will be equal to B Will be lower than C. Will be higher than D. Will be unrelated to
C. Will be higher than
Which condition is most likely to occur in patients having normal arterial waveform shape but low velocities across all vessels? A. Hypertension B. Low cardiac output C. Low hematocrit D. Venomotor tone
B. Low cardiac output
Atherosclerosis begins within : A. The adventitia B. The media C. The intima D. Both A and B E. All of the above
C. The intima
What must be known to convert the Doppler shift frequency spectrum into velocities? A. Doppler frequency B. Angle of incidence C. Speed of sound in tissue D. Ultrasound frequency E. All of the above
E. All of the above
What control should you adjust to increase the amplification applied to the color Doppler signal? A. Ensemble length B. Gain C. Scale D. Frame averaging (persistence)
B. Gain
Which of the following could be a source of color Doppler signal? A. Blood flow B. breathing motion C. Cardiac motion D. Transducer motion E. All of the above
E. All of the above
What is an advantage of using high-PRF Doppler? A. Ability to measure high velocities B. Improved range solution C. Higher frame rate D. Greater sensitivity to slow flow E. Improved spatial resolution
A. Ability to measure high velocities
What Doppler control removes frequencies below a given threshold, resulting in a clean zero baseline? A. High pass filter B. PRF C. Gain D. FFT
A. High pass filter
What limitation is present when you use high-PRF Doppler? A. Frame rate B. Spatial resolution C. Sensitivity to slow flow D. Range resolution E. Both C and D
E. Both C and D
