Chapter 6 copy

The pulser of an instrument automatically reduces the pulse repetition frequency for deeper imaging to avoid the \_______ \_______ artifact

a. comet tail
b. grating lobe
c. mirror image
d. range ambiguity

d

If an echo arrives 143 us after the pulse that produced it was emitted, it should be located at a depth of \___cm. If a second pulse was emitted 13 us before the arrival of this echo, it will be placed incorrectly at a depth of __cm.

a. 11, 1
b. 14, 13
c. 13, 14
d. 13, 13

a

If the propagation speed in a soft tissue path is 1.60 mm/us, a diagnostic instrument assumes a propagation speed too \__ and will show reflectors too \___ the transducer

a. high, close to
b. high, far from
c. low, close to
d. low, far from

c

Mirror image can occur with only one reflector.

True or False?

False

The most common artifact encountered in Doppler ultrasound is __

a. aliasing
b. range ambiguity
c. spectrum mirror image
d. location mirror image
e. electromagnetic interference

a

The fine texture in soft tissue indicates the excellent resolution that actually exists there.

True or false?

False

the fact that the beam, as it scans through tissue, has some nonzero width perpendicular to the scan plane results in the \______ \______ artifact

a. mirror image
b. range ambiguity
c. slice thickness/ section thickness
d. speed error

c

Refraction can cause shadowing

True or false

true

Reverberation results in added reflectors being imaged with equal __

a. depth
b. separation
c. width
d. brightness

b

In reverberation, subsequent reflections are \___ than previous ones.

a. shallower
b. brighter
c. weaker
d. stronger

c

Enhancement is caused by

a. strongly reflecting structures
b. weakly attenuating structures
c. strongly attenuating structures
d. refracting boundary
e. propagation speed error

b

which of the following can correct or eliminate aliasing

a. decreased PRF
b. decreased doppler angle
c. increased operating frequency
d. baseline shifting
e. more than one of the above

d

Shadowing results in decreased echo amplitudes.

True or false?

true

propagation speed error results in improper \__ position of a reflector on the display

a. lateral
b. axial

b

To avoid aliasing, a signal voltage must be sampled at least \_____ times per cycle.

a. 1
b. 2
c. 3
d. 4
e. 5

b

If the highest Doppler shift frequency present in a signal exceeds \_____ the PRF, aliasing will occur.

a. one tenth
b. one half
c. two times
d. five times
e. ten times

b

When Doppler gain is set too high, which artifact is likely to occur?

a. aliasing
b. range ambiguity
c. spectrum mirror image
d. location mirror image
e. speckle

c

which artifact should be suspected if one observes two gestational sacs when scanning through the rectus abdominis muscle

a. refraction
b. reverberation
c. speckle
d. enhancement

a

Range Ambiguity can occur in which of the following

a. imaging instruments
b. duplex instruments
c. pulsed wave doppler instruments
d. color flow instruments
e. all of the above

e

If the PRF is 4 kHz, which of the following doppler shifts will cause aliasing. kHz?

a. 1
b. 2
c. 3
d. 4
e. more than one of the above

e, 3&4

If the PRF is 10 kHz, which of the following doppler shifts will cause aliasing. kHz?

a. 1
b. 2
c. 3
d. 4
e. none of the above

e, anything above 5

There is no problem with aliasing as long as the Doppler shifts are \__ half the PRF

a. less than
b. approximately equal to
c. greater than
d. all of the above
e. none of the above

a

If doppler shift is 2.6 kHz, no aliasing would result with a PRF of 10 kHz.

true or false

true

When a pulse is emitted before all the echoes from the previous pulse have been received, which artifact occurs?

a. mirror image
b. range ambiguity
c. slice thickness
d. speed error

b

When a strong reflector is located in the scan plane, which of the following artifacts is likely to occur?

a. aliasing
b. range ambiguity
c. spectrum mirror image
d. location mirror image
e. speckle

d

Increasing the PRF to avoid aliasing can cause the following..

a. baseline shift
b. range ambiguity
c. spectrum mirror image
d. location mirror image
e. speckle

b

Which of the following decreases the likelihood of range ambiguity artifacts

a. decreasing operating frequency
b. decreasing PRF
c. decreasing doppler angle
d. baseline shift
e. increasing pulser output

b

Shadowing and enhancement are descriptions of \________ artifacts.

a. propagation
b. refraction
c. attenuation
d. reverberation

c

Echo reflections that produce bright and dark spots in the gray-scale image are called \________.

a. speckle
b. refraction
c. ring down
d. speed error

a

There must be \________ samples per cycle of Doppler shift to correctly obtain an image.

a. two
b. three
c. four
d. five

a

Which of the following is not a form of reverberation artifact?

a. Comet tail.
b. Ring down.
c. Mirror image.
d. Speckle.

d

Which artifact displaces structures axially?

a. Speed error.
b. Grating lobes.
c. Refraction.
d. Reverberation.

a

It may be possible to resolve slice thickness artifact by \________.

a. using harmonic imaging
b. using multiple focal zones
c. using a phased-array transducer
d. decreasing the imaging depth

a

Mirror-image artifact is a form of \________.

a. refraction
b. reverberation
c. speed error
d. grating lobes

b

Weakening of echoes distal to a strongly attenuating structure describes \________.

a. comet tail
b. enhancement
c. shadowing
d. ring down

c

Which of the following would most likely eliminate spectral aliasing?

a. Increasing the Doppler angle.
b. Increasing the transducer frequency.
c. Decreasing the pulse repetition frequency.
d. Increasing the depth of the sample volume.

a

Section thickness artifact is also called \________.

a. partial-volume artifact
b. ring-down artifact
c. comet-tail artifact
d. resonance phenomenon

a

Which type of artifact is most likely to produce a doubling of a single image?

a. Reflection.
b. Refraction.
c. Reverberation.
d. Section thickness.

b

Axial resolution is determined by \________ and lateral resolution is determined by \________.

a. pulse width; pulse length
b. pulse length; pulse width
c. pulse width; operating frequency
d. operating frequency; pulse length

b

Speckle artifact is most likely caused by \________.

a. refraction
b. interference
c. pulse width
d. multiple reflections

b

Mirror image is commonly seen around which structure?

a. Kidney.
b. Stomach.
c. Pancreas.
d. Diaphragm.

d

Increased intensity of echoes in the focal region of the beam is called \_______.

a. harmonics
b. shadowing
c. focal banding
d. enhancement

c

Enhancement of an echo results from a structure having \________ than surrounding structures.

a. higher impedance
b. lower density
c. higher attenuation
d. lower attenuation

d

Multiple reflections between two structures describes

a. refraction
b. mirror image
c. reverberation
d. speed error

c

How is detail resolution artifactual?

a. There is a failure to resolve two reflectors.
b. Actual size of structure is decreased.
c. Two adjacent structures are resolved.
d. Multiple reflections are displayed beneath the real reflector.

a

The comet-tail artifact is a case of \________.

a. refraction
b. resolution
c. attenuation
d. reverberation

d

Which of the following is an effect of refraction?

a. Shadowing at the edge of structures.
b. Two adjacent structures seen as one.
c. Incorrect representation of tissue densities.
d. Structures displayed medial from correct location.

a

Received echoes originating off center from the central beam are caused by \________.

a. speckle
b. speed error
c. range ambiguity
d. section thickness

d

Which of the following artifacts is exclusive to pulse-Doppler imaging?

a. Aliasing.
b. Mirror image.
c. Enhancement.
d. Range ambiguity.

a

Which of the following artifacts may display an incorrect shape of a structure?

a. Mirror image.
b. Reverberation.
c. Grating lobes.
d. Propagation speed error.

d

Which of the following artifacts would most likely place an echo at a depth much closer to the surface than it originated?

a. Speed error.
b. Mirror image.
c. Slice thickness.
d. Range ambiguity.

d

Additional beams emitted from an array transducer \__________.

a. are stronger than the main beam
b. duplicate structures laterally
c. demonstrate multiple reflections
d. produce echoes that are routinely imaged

b

Which of the following would likely demonstrate acoustic enhancement?

a. Liver.
b. Pancreas.
c. Gallbladder.
d. Falciform ligament.

c

The Nyquist limit is \________.

a. oversampling of the Doppler shifts
b. even and odd multiples of the frequency
c. the upper limit to the Doppler shift that can be properly detected
d. the number at which turbulence is detected

c

Which of the following will most likely cause range ambiguity?

a. High wall filter setting.
b. High operating frequency.
c. Multiple sample volumes.
d. High pulse repetition frequency.

d

Aliasing does not occur in \________.

a. color Doppler
b. duplex imaging
c. spectral Doppler
d. continuous-wave Doppler

d

The Nyquist limit describes the \________.

a. flow speed through a stenosis
b. driving force behind blood flow
c. resistance of blood flow in a straight tube
d. minimum number of samples required to avoid aliasing

d

If the pulse repetition frequency (PRF) is 6 kHz, which of the following Doppler shifts will cause aliasing?

a. 1 kHz.
b. 2 kHz.
c. 3 kHz.
d. 4 kHz.

d

Which of the following will always eliminate aliasing?

a. Using continuous wave Doppler.
b. Increasing the transducer frequency.
c. Decreasing the transducer frequency.
d. Increasing the pulse repetition frequency.

a

Which of the following types of artifacts can be beneficial?

a. Refraction.
b. Attenuation.
c. Propagation.
d. Reverberation.

b

When imaging deep structures, which of the following automatically occurs?

a. Frame rate increases.
b. Nyquist limit increases.
c. Pulse repetition period (PRP) is reduced.
d. Pulse repetition frequency (PRF) is reduced.

d

Under-sampling the Doppler shift is likely to cause \________.

a. aliasing
b. shadowing
c. a mirror image
d. range ambiguity

a

A duplication artifact associated with echoes interacting with a strong reflector is called \________.

a. cross-talk
b. comet tail
c. mirror image
d. partial volume

c

Clutter is also known as \__________.

a. noise
b. flash
c. speckle
d. cross-talk

b

Which of the following results from the underlying distribution of scatterers?

a. Speckle.
b. Ring-down.
c. Comet tail.
d. Section thickness.

a

Which of the following is a result of sound refraction?

a. Axial duplication of structures.
b. Displacement of structures axially.
c. Displacement of structures laterally.
d. Multiple equally spaced linear reflections.

c

Reflected echoes displaying falsely high amplitudes describe \________.

a. speckle
b. shadowing
c. enhancement
d. speed error

c

Color Doppler mirror image artifact is commonly displayed when imaging which of the following vessels?

a. Abdominal aorta.
b. Subclavian artery.
c. Internal jugular vein.
d. Common carotid artery.

b

A reduction in echo amplitude from reflectors behind a strongly reflecting structure is called \________.

a. speckle
b. comet tail
c. shadowing
d. enhancement

c

Equally spaced reflections that decrease in amplitude with increases in depth describe \________.

a. refraction
b. attenuation
c. reverberation
d. axial resolution

c

Which of the following artifacts appears as a series of closely spaced discrete echoes distal to a strongly reflective structure?

a. Ring down.
b. Comet tail.
c. Refraction.
d. Grating lobes.

b

Which of the following would least likely cause acoustic shadowing?

a. Gallstone.
b. Bowel gas.
c. Urinary bladder.
d. Uterine fibroid.

c

Which of the following is a common and convenient solution to eliminate aliasing?

a. Increasing transducer frequency.
b. Decreasing pulse repetition frequency.
c. Decreasing transducer frequency.
d. Shifting the baseline.

d

Which of the following can be considered a "cut-and-paste" technique of eliminating aliasing?

a. Shifting the baseline.
b. Increasing the pulse repetition frequency.
c. Decreasing the depth of the sample volume.
d. Increasing the Doppler angle.

a

Multiple sample gates will appear \________.

a. to manage range ambiguity
b. when utilizing power Doppler
c. when multiple focal zones are used
d. with a low pulse repetition frequency

a

If the propagation speed that exists over a path traveled is 1.44 mm/μs, the display will place the echo \________.

a. too far from the transducer
b. lateral from the actual location
c. too close to the transducer
d. medial from the actual location

a

Mirror imaging of a Doppler spectrum is most likely a result of the \________.

a. wall filter being set too low
b. Doppler gain being set too high
c. pulse repetition frequency being set too low
d. pulse repetition frequency being set too high

b

Increasing the pulse repetition frequency to avoid aliasing can cause \________.

a. clutter
b. speckle
c. mirror image
d. range ambiguity

d

The assumptions in the design of sonographic instruments include all of the following except \________.

a. sound travels in a straight line
b. sound travels at different speeds in soft tissue
c. echoes originate from objects located on the beam axis
d. echogenicity is a property of the structure

b

Edge shadowing is a result of \________.

a. refraction of the sound beam
b. attenuation of the sound beam
c. reflection of the sound beam
d. reverberation of the sound beam

a

Propagation speed error displaces structures \________.

a. axially
b. medially
c. laterally
d. anteriorly

a

The propagation group of sonographic artifacts includes \________.

a. comet tail, mirror image, shadowing
b. enhancement, focal banding, shadowing
c. grating lobe, enhancement, range ambiguity
d. mirror image, range ambiguity, slice thickness

d

The attenuation group of sonographic artifacts includes \________.

a. slice thickness, shadowing, and enhancement
b. reverberation, ring-down, and edge shadowing
c. comet tail, range ambiguity, and slice thickness
d. edge shadowing, focal banding, and enhancement

d

If the propagation speed through a medium is faster than 1.54 mm/μs, the reflector will be placed \________.

a. medial to the correct position
b. lateral to the correct position
c. deeper than the correct position
d. shallower than the correct position

d

Range ambiguity produces which error in anatomic imaging?

a. Range too long.
b. Range too short.
c. Doppler shift too low.
d. Doppler shift too high.

b

Section thickness artifact is a result of \________.

a. interference
b. pulse length
c. finite speed of sound in soft tissue
d. beam width perpendicular to scan plane

d

Edge shadowing is caused by

a. refraction
b. reverberation
c. propagation speed error
d. a highly attenuating structure

a

Spatial compounding can reduce attenuation artifacts.

true or false

true

Refraction can cause shadowing.

true or false

true

Artifacts can help and hinder proper interpretation and diagnosis.

true or false

true

Most modern instruments have implemented some form of speckle reduction techniques.

true or false

true

Beam width parallel to the scan plane causes partial volume artifact.

true or false

false

Grating lobes are essential for the proper operation of a linear phased array transducer.

true or false

false

The Nyquist limit is equal to the pulse repetition frequency (PRF).

true or false

false

Increasing the Doppler angle may eliminate aliasing.

true or false

true

Enhancement weakens the amplitude of structures distally.

true or false

false

Some artifacts are produced by improper equipment settings.

true or false

true

External influences can produce artifacts.

true or false

true

Aliasing is more common in color Doppler than in spectral Doppler.

true or false

true

Electromagnetic interference from nearby equipment can cloud the spectral display with lines or "snow."

true or false

true