Final Review Flashcards
All of the following are examples of postprocessing except ____.
a. volume presentation
b. B color
c. read zoom
d. write zoom
d
An analog-to-digital converter is also called a ______.
digitizer
An increase in the number of channels _____.
allows more precise control of the beam characteristics
Averaging sequential frames improves ______/
dynamic range
Brightness mode is also called _____.
gray-scale
Contrast resolution depends on _____ of bits per pixel.
number
Displays have dynamic ranges up to ___ dB.
30
Filtering of the sound beam is used to eliminate _____.
frequencies outside of the bandwidth
Gain the ratio of ______.
amplifier output to input electric power
Holding and displaying one frame out of the sequence is known as ____.
freeze
If the operating frequency is reduced,
maximum penetration depth increases
In order to image deeper structures, the
PRF needs to be decreased
Increasing the frame rate improves
temporal resolution
Maximum amplifier gain is determined by
noise
Normally the number of channels does not exceed the number of _____
elements in the transducer
Pixel interpolation, persistence, and panoramic imaging are examples of
preprocessing
Retention of previous frames while new echo information is added in the same scanning plane is called
panoramic imaging
Storage of the last several frams acquired before freezing is called
cine loop
The ____ and ____ determine the maximum imaging depth.
attenuation; maximum amplifier gain
The ____ determines how much amplification is accomplished in the amplifier.
gain control
The _____ determines the brightness of the echoes on the display.
digital-to-analog converter
The direct(s) the driving voltages from the pulser to the transducer during transmission and directs returning echo voltages to amplifiers during reception.
transmit/receive switch
The _____ drive(s) the transducer forming the beam that sweeps through the tissue to be imaged
pulser
The _____ is where the action originates.
beam former
The ability of a gray-scale display to distinguish between echoes of slightly different intensities is called _____.
contrast
The averaging of sequential frames together to provide a smoother image appearance is called _____
persistence
The display form that presents the depth in the vertical axis and the amplitude of the echo in the horizontal axis is _____.
A mode
The frequency of the _____ determines the frequency of the resulting ultrasound pulse
voltage pulse
The harmonic beam is much narrower than the fundamental, improving _____
lateral resolution
The maximum frame rate permitted for a 15 cm penetration depth, three focuses, and 200 scan lines per frame is _____.
8.5
The pulse repetition frequency (PRF) in real time imaging typically ranges from
4-15 kHz
The purpose of a bandpass filter is to
eliminate frequencies outside the echo bandwidth
The ratio of the largest to the smallest amplitude that a system can handle is called the
dynamic range
Time gain compensation amplifiers compensate for _____ decibels of attenuation
60
To avoid echo misplacement _____
all echoes must be received before another pulse is emitted
To receive information for display at a rapid rate, it is desirable to use a ______
high pulse repetition frequence
Volume imaging is accomplished by
acquiring many parallel two dimensional scans
What is the macimum penetration depth with a frame rate of 32 frames per second and a line density of 100 lines per frame and using only one focus?
24 cm
When gain is too high, which of the following occurs?
a. difference in echo strength are lost
b. contrast resolution is improved
c. weak echoes are not imaged
d. Temporal resolution is reduced
a
When the fundamental frequency is filtered out, which of the following occurs?
a. pixel interpolation
b. harmonic frequencies
c. spatial compounding
d. volume imaging
b
Which imaging technique is most likely to visualize a structure beneath a calcification?
a. pixel interpolation
b. panoramic imaging
c. harmonic imaging
d. spatial compounding
d
Which of the following constitutes a reception channel?
a. beam former, signal processor, image processor, and display
b. Beam former, pulser, amplifier, and scan converter
c. Elements, pulser, signal processor, and delay path
d. elements, amplifier, digitizer, and delay path
d
Which of the following digitally filters, detects, and compresses echo data?
a. digitizer
b. summer
c. signal processor
d. beam former
c
Which of the following is not an advantage of harmonic imaging>
a. increased lateral resolution
b. reduction in superficial reverberation artifacts
c. elimination of grating lobe artifacts
d. wide primary beam
d
Which of the following operator controls adjusts compression?
a. depth
b. time gain compensation
c. dynamic range
d. overall gain
c
Which of the following reformats data into image form for processing, storage, and display?
a. summer
b. digitizer
c. signal processor
d. beam former
b
Which of the following techniques is considered the imaging version of palpation?
a. elastography
b. panoramic imaging
c. pixel interpolation
d. volume imaging
a
Which system component produces the electrical voltages that drive the transducer?
pulser
Which system control equalizes amplitudes by different reflector depths?
time gain compensation
_____ determines how echo data stored in memory appear on the display.
postprocessing
A duplication artifact associated with echoes interacting with a strong reflector is called ____
mirror-image
A reduction in echo amplitude from reflectors behing a strongly reflecting structure is called ____.
shadowing
Aliasing does not occur in _____.
continuous wave Doppler
Axial resolution is determined by _____ and lateral resolution is determined by _____.
pulse length; pulse width
Clutter is also known as ____.
flash
Echo reflections that produce bright and dark spots in the gray-scale image are called ______.
speckle
Edge shadowing is a result of
refraction of the sound beam
Edge shadowing is caused by
refraction
Enhancement of an echo results from a structure having _____ than surrounding structures
lower attenuation
Equally spaced reflections that decrease in amplitude with increases in depth describe ____.
reverberation
How is detail resolution artifactual?
There is a failure to resolve two reflectors
If the propagation speed that exists over a path traveled is 1.44 mm/us, the display will place the echo _____
too far from the transducer
If the propagation speed through a medium is faster than 1.54 mm/us, the reflector will be placed ______
shallower than the correct position
If the PRF is 6 kHz, which of the following Doppler shifts will causing aliasing?
a. 1 kHz
b. 2 kHz
c. 3 kHz
d. 4 kHz
d
Increasing the pulse repetition frequency to avoid aliasing can cause _____.
range ambiguity
IT may be possible to resolve slice thickness artifact by:
using harmonic imaging
Mirror-image artifact is a form of
reverberation
Mirror-image is commonly seen around which structure?
diaphragm
Mirror-imaging of a Doppler spectrum is most likely a result of the _____
Doppler gaini being set too high
Multiple reflections between two structures describe:
reverberation
Multiple sample volumes will appear _____.
to manage range ambiuity
Propagation speed error displaces structures
axially
Received echos originating off center from the central beam are caused by
section thickness
Reflected echoes displaying falsely high amplitudes descrie
enhancement
Section thickness artifact is a result of
beam width perpendicular to scan plane
Shadowing and enhancement are descriptions of _____ artifacts.
attenuation
Speckle artifact is most likely caused by
interference
The Nyquist limit describes the
minimum number of samples required to avoid aliasing
The Nyquist limit is
the upper limit to the Doppler shift that can be properly detected
The ____ and _____ artifacts are both forms of reverberation
comet tail; mirror image
The assumptions in the design of sonographic instruments include all of the following except
a. echogenicity is a property of the structure
b. sound travels in a straight line
c. echoes originate from objects located on the beam axis
d. sound travels at different speeds in soft tissue
d
The attenuation group of sonographic artifacts includes
edge shadowing
focal banding
enhancement
The propagation group of sonographic artifacts include _____
mirror-image
range ambiguity
slice thickness
Under-sampling the Doppler shift is likely to cause
aliasing
Weakening of echoes distal to a strongly attenuating structure describes
shadowing
When imaging deep structures, which of the following automatically occurs?
a. PRF reduced
b. PRP reduced
c. Nyquist limit increases
d. Frame rate increases
a
Which artifact displaces structures axially?
speed error
Which of the following artifacts appears as a series of closely spaced discrete echoes distal to a strongly reflective structure?
a. comet tail
b. grating lobes
c. refraction
d. ring down
a
Which of the following artifacts is exclusive to pulse-Doppler imaging?
a. aliasing
b. mirror image
c. range ambiguity
d. enhancement
a
Which of the following artifacts may display an incorrect shape of a structure?
a. grating lobes
b. mirror image
c. propagation speed error
d. reverberation
c
Which of the following artifacts would most likely place an echo at a depth much closer to the surface than it originated?
a. mirror image
b. speed error
c. range ambiguity
d. slice thickness
c
Which of the following can be considered a “cut-and-paste” technique of eliminating aliasing?
a. decreasing the depth of the sample volume
b. increasing the Doppler angle
c. Increasing the pulse repetition frequency
d. Shifting the baseline
d
Which of the following is a result of sound refraction?
a. displacement of structures axially
b. axial duplication of structures
c. multipe equally spaced linear reflections
d. displacement of structures laterally
d
Which of the following is an effect of refraction?
a. incorrect representation of tissue densities
b. structures displayed medial from correct location
c. shadowing at the edge of structures
d. two adjacent structures seen as one
c
Which of the following results from the underlying distribution of scatterers?
a. comet tail
b. ring down
c. speckle
d. section thickness
c
Which of the following types of artifacts can be beneficial?
a. reverberation
b. propagation
c. attenuation
d. refraction
c
Which of the following will always eliminate aliasing?
a. increasing the transducer frequency
b. decreasing the transducer frequency
c. using continuous wave Doppler
d. Increasing the pulse repetition frequency
c
Which of the following would least likely cause acoustic shadowing?
a. uterine fibroid
b. gallstone
c. urinary bladder
d. bowel gas
c
Which of the following would most likely eliminate spectral aliasing?
a. Increasing the Doppler angle
b. Increasing the depth of the sample volume
c. Decreasing the pulse repetition frequency
d. increasing the transducer frequency
a
Which type of artifact is most likely to produce a doubling of a single image?
refraction
A Doppler shift at 60 degrees is _____. What would it be at 0 degrees?
one half of
A change in frequency caused by motion of a source or reflector defines:
Doppler effect
A nonsteady flow with acceleration and deceleration over the cardiac cycle is called:
pulsatile flow
Continuous wave Doppler shifts are detected within the:
overlapped region of the transmitting and receiving beams
Determining the direction of the Doppler shift voltages is accomplished by the:
phase quadrature detector
Doppler measurements are not reliable at Doppler angles greater than ____ degrees.
60
Doppler shift does not depend on the:
flow direction
Echoes arrive from the sample volume depth at a rate equal to:
the pulse repetition frequency
For a given flow, the greater the Doppler angle, the
less the Doppler shift
Gases, nutrients, and waste products are exchanged through the walls of:
capillaries
If pressure difference in a straight vessel increase, the flow rate _____.
increases
Motion toward the transducer demonstrates ______.
a positive Doppler shift
Poise is a unit given for ______.
viscosity
Poiseuille’s equation states that, if the flow rate increases, the
tube diameter has increases
Poiseuille’s equation states that, if the flow rate increases, the
tube diameter has increased
Resistance to flow offered by a fluid in motion describes:
viscosity
Sound reflects totally at the wall-blood boundary once the Doppler angle is less than _____ degrees.
30
Spectral broadening may be produced by:
beam spreading in arrays
The Doppler equation relates the Doppler shift to the:
flow speed and frequency
The amount of blood passing a point per unit of times defines:
volumetric flow rate
The angle of incidence is not important with which Doppler display?
Power
The decreased pressure in regions of high flow speed is called _____.
Bernoulli effect
The difference between the emitted frequency and the echo frequency returning from a moving scatterer?
Doppler shift
The fast Fourier transform derives the Doppler _____
spectrum
The horizontal presentation in the spectral display represents _____.
time
The resistance of the _____ accounts for about one half of the total resistance in the systemic circulation.
arterioles
The volumetric flow rate is equal to _____.
average flow rate across the vessel multiplied by the cross-sectional area of the vessel
The width of the sample volume is determined by the:
beam width and sample volume depth
Turbulent flow is a form of _____ flow.
nonlaminer
Variance color maps demonstrate a change of hues from:
left to right
Vertical thickening of the spectral tracing is called _____.
spectral broadening
What advantage does spectral analysis have when compared to other Doppler techniques? Spectral analysis ______.
displays peak systolic velocities
What is required for flow to occur?
pressure difference
What is the driving force behind blood flow?
pressure
What type of blood flow demonstrates layers of fluid sliding over each other?
laminar
Which flow type demonstrates a flow velocity that is essentially constant across the vessel?
plug
Which matter is considered a fluid?
gases and liquids
Which of the following Doppler displays cannot determine flow direction?
a. color
b. spectrum
c. continuous wave
d. power
d
Which of the following Doppler techniques must be time shared?
a. color Doppler
b. Duplex imaging
c. continuous wave
d. spectral analysis
b
Which of the following is an advantage of pulsed Doppler?
a. Higher operating frequencies can be utilized
b. Higher frequency shifts can be displayed without aliasing
c. Depth of sample volume can be accurately selected
d. sensitivity of low flow velocities is increased
c
Which of the following pulsed Doppler techniques is the most likely to demonstrate slow flow velocities in deep vessels?
a. spectral analysis
b. color Doppler
c. Duplex imaging
d. Power Doppler
d
Which system control eliminates low-frequency Doppler shifts?
wall filter
Which type of blood flow demonstrates a chaotic flow patter?
turbulent
Which type of blood flow would demonstrate the narrowest range of Doppler shift frequencies?
plug
With color Doppler imaging, the priority control _____.
selects which gray-scale echo strength will demonstrate color
_____ describes the volumetric flow rate as a constant
Continuity rule
An imaginary laser-thin transmitted ultrasound beam that can be thought of as producing excellent detail resolution throughout the image describes a _____
virtual transmission beam
Improvements in Doppler operation with Principle 2 include all of the following except:
a. simultaneous gray-scale, color-Doppler, and spectral Doppler
b. prospective sample volume
c. flow velocity vector mapping
d. automatic aliasing correction
b
Principle 2 improvements in anatomic imaging include all of the following except:
a. contrast resolution
b. sensitivity
c. penetration
d. axial resolution
d
The retrospective beam-forming process occurs in the _____.
image former
Which of the following contributes to improved temporal resolution in Principle 2?
a. broad physical beams
b. fewer pulses
c. both a and b
d. none are correct
c
