Artifacts Chap 8

Question 1

What is Speed Error in ultrasound?

Answer 1

Structure appears deeper or more shallow than reality

Speed error can lead to misinterpretation of the actual depth of structures.

Question 2

Define refraction artifact in ultrasound.

Answer 2

A structure appears laterally displaced or two structures, one real, and one fake rest side-by-side

Refraction can cause confusion in identifying the true location of structures.

Question 3

What is reverberation in ultrasound?

Answer 3

Sound bouncing back-and-forth between two structures, resulting in replication of the structure depth

This artifact can create multiple echoes of the same structure.

Question 4

What characterizes the ring down artifact?

Answer 4

A special case of reverberation which occurs within an air/fluid field structure, producing a bright tail inferior to structure

Ring down artifacts are often seen in cases involving gas bubbles.

Question 5

Explain the comet tail artifact.

Answer 5

Reverberation artifact that occurs with the name of metallic or solid structure, having a bright tail inferior to structure

This artifact can obscure the true anatomy beneath the metallic object.

Question 6

What is multipath artifact?

Answer 6

Sound gets redirected by a specular reflector and reflects back to the transducer, creating an artificial structure deeper than the true structure

Multipath can mislead the interpretation of the depth of the actual structure.

Question 7

Define mirror artifact.

Answer 7

Sound reflects from a smooth specular reflector toward another structure, and then back to the mirror, causing a symmetric appearance

This artifact can create the illusion of additional structures in the image.

Question 8

What is the lateral resolution limit?

Answer 8

The inability to distinguish two side-by-side structures

This can affect the clarity of images where adjacent structures are present.

Question 9

Define elevation resolution limit.

Answer 9

The inclusion in the image from tissue/structures

This limit affects the accuracy of the depth of structures in the image.

Question 10

What are grading lobes in ultrasound?

Answer 10

Caused by off-axis reflectors, making two structures appear side-by-side, but only one exists

Grading lobes can lead to misinterpretation of the actual number of structures.

Question 11

Define axial resolution limit.

Answer 11

The inability to distinguish two structures separated by depth

This limit can affect the assessment of structures that are close in depth.

Question 12

What does enhancement refer to in ultrasound artifacts?

Answer 12

Appears as a region of brighter echoes inferior to more superficial structures with less attenuation than normal

Enhancement can indicate the presence of fluid-filled structures.

Question 13

What is shadowing in ultrasound?

Answer 13

The reciprocal of enhancement, appearing as a dark region inferior to a structure that attenuates more than normal

Shadowing can obscure underlying structures and complicate diagnosis.

Question 14

Define speckle in ultrasound.

Answer 14

Creates the apparent tissue texture and results from constructive and destructive interference from the reflection tissues

Speckle can affect the interpretation of tissue characteristics.

Question 15

What is aliasing in Doppler artifacts?

Answer 15

Occurs when detected mean velocity is greater than the mean velocity determined by the color bars, causing a wrap around the color bar

Liaising can lead to inaccurate velocity measurements.

Question 16

Define color bleed in Doppler imaging.

Answer 16

Limited axial resolution results in color bleeding over regions occupied by tissue

Color bleed can obscure the true flow information in the imaging.

Question 17

What causes color noise speckle?

Answer 17

Caused by receiver gain being too high, most commonly in regions where flow is present

This artifact can complicate the assessment of flow dynamics.

Question 18

What is color drop out?

Answer 18

Occurs if wall filters are set too high, filtering out lower velocity flow

This may result in missing important hemodynamic information.

Question 19

Define range ambiguity in Doppler imaging.

Answer 19

Occurs when the signal is not detected correctly from the specified gate depth

Range ambiguity can misrepresent the actual depth of flow.

Question 20

What is circuit saturation in Doppler imaging?

Answer 20

Known as valve clicks, appears as a bright white spike symmetric about the baseline with a loud click or popping sound

Circuit saturation can affect the quality of the Doppler signal.

Question 21

What happens during signal drop out?

Answer 21

Occurs when wall filters are set higher than frequency, causing no signal to be present for low velocity flow

Signal drop out can lead to incomplete assessment of flow.

Question 22

Define spectral broadening in Doppler artifacts.

Answer 22

Results in a spread of the Doppler spectrum, making the peak velocity appear higher than reality

Spectral broadening can complicate the interpretation of flow velocities.

Question 23

What is blossoming in Doppler imaging?

Answer 23

When the Doppler signal becomes excessively high from excessive Doppler receive gain, giving an increased peak velocity measurement

Blossoming can mislead clinicians regarding the actual hemodynamics.

Question 24

What are the key factors affecting axial resolution?

Answer 24

Limited axial resolution, limited lateral resolution, limited elevation resolution, beam aberration

Aberration affects axial, lateral, and elevation resolution

Question 25

What are locational artifacts in imaging?

Answer 25

Structures appearing displaced in the image ## Footnote Examples include refraction, reverberation, comet tail, ring down, multipath, grading, lobes, side lobes, speed error, range ambiguity, mirror images

Question 26

What types of artifacts arise from axial resolution?

Answer 26

Speed, air, reverberation, tail, ring down, mirroring, multipath ## Footnote These artifacts can distort the perceived location or quality of the signal

Question 27

What artifacts are associated with lateral resolution?

Answer 27

Grading, lobes and side lobes, refraction ## Footnote These can lead to inaccuracies in the representation of structures

Question 28

Which artifacts are linked to elevation resolution?

Answer 28

Speed error, range ambiguity ## Footnote These artifacts can affect the vertical positioning of structures

Question 29

What are attenuation artifacts and their effects?

Answer 29

Change in intensity of the signal and potentially the location of a signal ## Footnote Includes acoustic shadowing, enhancement, reverberation, tail, ring down, refraction, speckle

Question 30

What is the impact of phase-related artifacts?

Answer 30

Deep focusing effect or loss of detail resolution ## Footnote Includes speckle and beam aberration

Question 31

Fill in the blank: Artifacts from axial resolution include _______.

Answer 31

speed, air, reverberation, tail, ring down, mirroring, multipath

Question 32

Fill in the blank: Artifacts from lateral resolution include _______.

Answer 32

grading, lobes and side lobes, refraction

Question 33

True or False: Attenuation artifacts can result in a change in intensity of the signal.

Answer 33

True

Question 34

True or False: Phase-related artifacts have no impact on detail resolution.

Answer 34

False

Question 35

What is the refraction artifact?

Answer 35

Results in a lateral displacement of the structure within the image ## Footnote Refraction occurs when sound waves change direction as they pass through different mediums.

Question 36

What causes reverberation artifacts?

Answer 36

Caused by sound which reverberates between two or more structures ## Footnote Reverberation is more likely when there is a large acoustic competence mismatch.

Question 37

How is reverberation affected by angles?

Answer 37

Reverberation is highly angle dependent ## Footnote The angle of incidence can significantly influence the degree of reverberation observed.

Question 38

What is the consequence of reverberation in imaging?

Answer 38

Causes all structures and tissues to be replicated ## Footnote This can lead to misinterpretation of the anatomical structures.

Question 39

What is speed error in ultrasound imaging?

Answer 39

Occurs when propagation speed is different than 1540 meters per second, resulting in incorrect depth display ## Footnote Speed errors can distort the perceived location of structures in the image.

Question 40

What modalities suffer from range ambiguity?

Answer 40

All pulse wave modalities ## Footnote Range ambiguity artifacts occur due to reflected data from previous transmissions.

Question 41

What causes shadowing artifacts?

Answer 41

Caused by excessive reflection, absorption, or refraction ## Footnote Shadowing can obscure structures behind the shadowing object.

Question 42

What is ED shadowing and what causes it?

Answer 42

Caused by excessive refraction and commonly occurs from edges of vessels and bones ## Footnote This type of shadowing can significantly affect diagnostic imaging.

Question 43

What does the figure of eight artifact resemble?

Answer 43

Looks like a figure 8 ## Footnote This artifact occurs from the M Platzer septal occluder device.