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Ultrasound Physics > Harmonics & Doppler > Flashcards

Harmonics & Doppler Flashcards

1
Q 
Which of the following flow patterns is associated with cardiac contraction?
A. phasic
B. spontaneous
C. steady
D. pulsatile
E. continuous
A

D. pulsatile

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2
Q 
Which of the following terms does not belong with the others?
A. phasic
B. spontaneous
C. pulsatile 
D. venous
A

C. pulsatile

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3
Q 
Which of the following is not associated with laminar flow?
A. layered
B. normal
C. aligned
D. smooth
E. chaotic
A

E. chaotic

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4
Q 
Which of the following is not associated with turbulent flow?
A. parabolic
B. eddy
C. vortex
D. swirling
E. spectral broadening
A

A. parabolic

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5
Q 
What is the primary reason blood moves from one location to another?
A. energy gradient
B. anemia
C. pressure gradient
D. systole 
E. friction
A

A. energy gradient

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6
Q 
All of the following decrease the flow energy of a fluid except: 
A. frictionless loss
B. viscous loss
C. inertial loss
D. velocity loss
A

D. velocity loss

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7
Q 
Which of the following causes the greatest amount of inertial energy loss?
A. pulsatile flow
B. flow through a stenosis
C. phasic flow
D. steady flow
E. parabolic flow
A

B. flow through a stenosis

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8
Q

The arterial blood pressure of a supine individual is 120 mmHg. What is the hydrostatic pressure at the subject’s ankle?

A

0 mmHg

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9
Q

The atrial blood pressure of a supine individual is 120 mmHg. What is the hydrostatic pressure at the subject’s hips?

A

0 mmHg

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10
Q

The atrial blood pressure os a standing individual is 120 mmHg. What is the hydrostatic pressure at the subject’s ankle?

A

A 100 mmHg

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11
Q

The atrial blood pressure of a standing individual is 120 mmHg at the level of the heart. What is the measured blood pressure at the subject’s ankle?

A

E. 220 mmHg

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12
Q

What happens to venous return to the heart when an individual inhales?

A

A. increases

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13
Q

What happens to venous flow in the legs when an individual inhales?

A

B. decreases

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14
Q

What happens to the diaphragm when an individual breathes out?

A

A. it ascends into the thorax

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15
Q

What happens to venous return to the heart when an individual exhales?

A

B. decreases

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16
Q

What happens to venous flow in the legs when an individual exhales?

A

A. increases

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17
Q 
The Doppler effect is observed as a change in \_\_\_\_\_ and has units of \_\_\_\_.
A. amplitude, watts
B. power, watts
C. frequency, per second
D. wavelength, millimeters
A

C. frequency, per second

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18
Q 
In clinical imaging, which reflections produce most relevant Doppler shifts?
A. blood vessels
B. blood plasma
C. platelets
D. red blood cells
A

D. red blood cells

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19
Q

If red blood cells are traveling toward a transducer, the frequency emitted by the transducer is _____ the frequency reflects from the red blood cells.
A. greater than
B. equal to
C. less than

A

C. less than

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20
Q 
In standard Doppler, what is true about the reflected frequency produced by blood cells traveling away from the transducer?
A. it is in the audible range
B. it is ultrasonic
C. it exceeds the transmitted frequency 
D. it equals the transmitted frequency
A

B. it is ultrasonic

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21
Q

What is the range of Doppler shifts commonly measures in clinical exams?

A

C. -0.02 MHz to 0.02 MHz

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22
Q

When red blood cells move away from a transducer, the frequency of the wave reflected from the red cells is ___ the frequency emitted by the transducer.

A

B. Less than

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23
Q

What information does the doppler shift furnish concerning the blood cells that produce it?

A

C. velocity

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24
Q

Blood moving at a velocity of 2 m/s creates a Doppler frequency of 3,000 Hz. What will the Doppler shift be if the velocity increases to 4 m/s

A

D. 6,000 Hz

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25
Q 
Two ultrasound transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest velocities?
A. the 2.5 MHz exam
B. the 5 MHz exam
C. neither
D. cannot be determined
A

C. neither

26
Q

Two ultrasound transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest Doppler shift?

A

B. the 5 MHz exam

27
Q

When using a 4 MHz transducer, a Doppler shift of 3,000 Hz is recorded. What will the Doppler shift be when a 2 MHz transducer is used?

A

C. 1,500 Hz

28
Q 
Doppler does not always provide a valid estimate of the speed of blood cells because the shift is related to the \_\_ of the angle between the direction of the beam and the direction of blood flow.
A. sine
B. tangent
C. cosine
D. contangent
29
Q 
Two otherwise identical Doppler studies are performed, except that the angle between flow and the sound beam is 0 degrees in the first study and 60 degrees in the second. The velocity measured in the first study is 2 m/s. What velocity will be measured in the second study?
A. 2 m/s 
B. 4 m/s
C. 1 m/s 
D. cannot be determined
30
Q 
What is true of the Doppler shift when the sound beam is normally incident to the velocity if the red blood cells?
A. it is at maximum
B. it is half of the maximum
C. it is absent
D. it is at minimum
A

C. it is absent

31
Q 
A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of the sound beam is \_\_\_. 
A. 10 degrees
B 90 degrees
C. 180 degrees
D. 270 degrees
A

C. 180 degrees

32
Q

T/F: The appearance of negative velocities on the spectral display of a continuous wave Doppler exam always indicates that red blood cells are moving away from the transducer.

33
Q

A minimum of two distinct piezoelectric crystals are in the transducer

34
Q

Problems with aliasing significantly limit its clinical utility.

35
Q

Frequencies measured at the transducer are produced from many different locations along the ultrasonic beam.

36
Q

They duty cycle of the continuous wave is 100%

37
Q 
All of the following are related to dedicated continuous wave Doppler transducers except
A. wide bandwidth
B. high quality factor
C. higher sensitivity
D. range ambiguity
A

A. wide bandwidth

38
Q

A duplex ultrasound system displays ____ information

A

C. two-dimensional image and M-mode

39
Q 
All of the following are associated with a CW Doppler transducer except: 
A. narrow bandwidth
B. increased sensitivity
C. backing material 
D. high Q factor
A

C. backing material

40
Q 
The information that is processed by a standard duplex ultrasound system includes all of the except:
A. attenuation
B. amplitude
C. frequency
D. time of travel
A

A. attenuation

41
Q

T/F: The appearance of negative velocities in a pulsed Doppler display always indicates that red blood cells are moving away from the transducer.

42
Q

With pulsed Doppler, what term is used to describe a very high positive Doppler shift that is displayed as a negative waveform

A

D. aliasing

43
Q

The highest Doppler frequency without the appearance of aliasing is called the __ and is equal to ___.

A

D. Nyquist limit, half of the emitted PRF

44
Q

T/F: In a pulsed Doppler exam, the use of a higher transducer frequency increases the likelihood that aliasing will appear.

45
Q

T/F: The higher the pulse repetition frequency of a Doppler exam, the more likely aliasing is to occur.

46
Q

A system has three transducers with frequencies of 7.5 MHz, and 3.25 MHz. Aliasing appears while using the 5.0 MHz transducer during a pulsed Doppler exam. What should the sonographer do?

A

A. use the 3.25 MHz transducer

47
Q

The frequency of a pulsed Doppler wave is 6 MHz, and the PRF id 5 kHz. What is the maximum Doppler shift that can be recorded without aliasing?

A

D. 2.5 kHz

48
Q

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

A

C. selection of another imaging view that provides a greater pulse repetition period

49
Q

T/F: TGC cannot be used with continuous wave Doppler.

50
Q 
Which of the following determines the gray scale in a Doppler spectrum?
A. number of reflectors
B. velocity
C. frequency shift
D. laminar flow
A

A. number of reflectors

51
Q 
Which choice relates to the presence of gray shades in a Doppler spectrum?
A. velocity
B. frequency shift
C. amplitude of the echo
D. laminar flow
A

C. amplitude of the echo

52
Q

T/F: Color flow Doppler exams tend to have lower temporal resolution than traditional two-dimensional, real-time imaging.

53
Q

T/F: Color flow Doppler imaging incorporates pulsed Doppler principles and provides range resolution.

54
Q

T/F: Color flow Doppler systems display anatomical data in gray scale while simultaneously displaying flow information in color.

55
Q

T/F: On a color Doppler image, red always represents flow toward the transducer, whereas blue indicates flow away from the transducer

56
Q

T/F: Absence of color on a color Doppler image always indicates a region of no blood flow

57
Q 
The two most common color maps used in color flow imaging are:
A. variance and direct
B. variance and velocity
C. turbulence and variance 
D. power and velocity
A

B. variance and velocity

58
Q

T/F: Variance mode color maps may be identified by side-to-side changes in the color bar, whereas velocity mode color maps only change color vertically.

59
Q

T/F: Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are laminar.

60
Q

T/F: Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent.

Ultrasound Physics (2 decks)

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