Deck 6: Artifacts

Question 1

Shadowing and enhancement are descriptions of ________ artifacts.

A) propagation
B) refraction
C) attenuation
D) reverberation

Answer 1

C
Attenuation artifacts include enhancement,shadowing,edge shadowing,and focal enhancement (focal banding).

Question 2

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

A) two
B) three
C) four
D) five

Answer 2

A
At least two samples per cycle of the desired Doppler shift must be made for the image to be correctly obtained.

Question 3

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

A) Comet tail.
B) Ring down.
C) Mirror image.
D) Speckle.

Answer 3

D
Reverberation artifact demonstrates multiple reflections as seen with ring-down,mirror-image,and comet-tail artifacts.Speckle is a result of the interference effects of the scattered sound.

Question 4

Which artifact displaces structures axially?

A) Speed error.
B) Grating lobes.
C) Refraction.
D) Reverberation.

Question 5

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

Question 6

Mirror image is commonly seen around which structure?

A) Kidney.
B) Stomach.
C) Pancreas.
D) Diaphragm.

Question 7

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

A) harmonics
B) shadowing
C) focal banding
D) enhancement

Question 8

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.

Question 9

Mirror-image artifact is a form of ________.

A) refraction
B) reverberation
C) speed error
D) grating lobes

Question 10

Speckle artifact is most likely caused by ________.

A) refraction
B) interference
C) pulse width
D) multiple reflections

Question 11

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

A) Reflection.
B) Refraction.
C) Reverberation.
D) Section thickness.

Question 12

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

Question 13

The comet-tail artifact is a case of ________.

A) refraction
B) resolution
C) attenuation
D) reverberation

Question 14

Multiple reflections between two structures describes

A) refraction
B) mirror image
C) reverberation
D) speed error

Question 15

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

A) comet tail
B) enhancement
C) shadowing
D) ring down

Question 16

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.

Question 17

Section thickness artifact is also called ________.

A) partial-volume artifact
B) ring-down artifact
C) comet-tail artifact
D) resonance phenomenon

Question 18

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

Question 19

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.

Question 20

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

A) higher impedance
B) lower density
C) higher attenuation
D) lower attenuation

Question 21

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

Question 22

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

A) speckle
B) speed error
C) range ambiguity
D) section thickness

Question 23

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.

Question 24

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.

Question 25

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.

Question 26

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

A) Aliasing.
B) Mirror image.
C) Enhancement.
D) Range ambiguity.

Question 27

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.

Question 28

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

Question 29

Which of the following would likely demonstrate acoustic enhancement?

A) Liver.
B) Pancreas.
C) Gallbladder.
D) Falciform ligament.

Question 30

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.

Question 31

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.

Question 32

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

Question 33

Clutter is also known as __________.

A) noise
B) flash
C) speckle
D) cross-talk

Question 34

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

Question 35

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

A) Speckle.
B) Ring-down.
C) Comet tail.
D) Section thickness.

Question 36

Reflected echoes displaying falsely high amplitudes describe ________.

A) speckle
B) shadowing
C) enhancement
D) speed error

Question 37

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

A) aliasing
B) shadowing
C) a mirror image
D) range ambiguity

Question 38

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.

Question 39

Which of the following types of artifacts can be beneficial?

A) Refraction.
B) Attenuation.
C) Propagation.
D) Reverberation.

Question 40

Aliasing does not occur in ________.

A) color Doppler
B) duplex imaging
C) spectral Doppler
D) continuous-wave Doppler

Question 41

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

Question 42

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

Question 43

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

Question 44

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

A) speckle
B) comet tail
C) shadowing
D) enhancement

Question 45

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.

Question 46

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

Question 47

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

Question 48

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

Question 49

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 frequenty.
D) Shifting the baseline.

Question 50

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

Question 51

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.

Question 52

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

A) refraction
B) attenuation
C) reverberation
D) axial resolution

Question 53

Which of the following would least likely cause acoustic shadowing?

A) Gallstone.
B) Bowel gas.
C) Urinary bladder.
D) Uterine fibroid.

Question 54

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.

Question 55

Propagation speed error displaces structures ________.

A) axially
B) medially
C) laterally
D) anteriorly

Question 56

Edge shadowing is caused by

A) refraction
B) reverberation
C) propagation speed error
D) a highly attenuating structure

Question 57

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

Question 58

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

Question 59

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

A) clutter
B) speckle
C) mirror image
D) range ambiguity

Question 60

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.

Question 61

Lateral duplication of a single structure into two separate structures describes mirror imaging artifact.

Question 62

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

Question 63

Some artifacts are produced by improper equipment settings.

Question 64

Duplication of the spectral display can occur when the Doppler angle is near 90 degrees.

Question 65

High pulse repetition frequencies can result in Doppler range ambiguity artifacts.

Question 66

External influences can produce artifacts.

Question 67

Artifacts can help and hinder proper interpretation and diagnosis.

Question 68

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

Question 69

Increasing the Doppler angle may eliminate aliasing.

Question 70

Enhancement weakens the amplitude of structures distally.

Question 71

Mirror image artifact is not a factor in color Doppler imaging.

Question 72

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

Question 73

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

Question 74

Operating frequency reduction reduces the Doppler shift.

Question 75

Refraction can cause shadowing.

Question 76

Aliasing is caused by over-sampling of the Doppler shifts.

Question 77

Cross-talk can occur when receiver gain is set too high.

Question 78

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

Question 79

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

Question 80

Spatial compounding can reduce attenuation artifacts.