CH. 21 Artifacts- DMS 113 Review Questions

Axial or lateral resolution artifact causes two adjacent structures to appear as one. T/F?

T

Axial or lateral resolution artifact causes increase from actual size of a structure. T/F?

T

Axial or lateral resolution artifact results in loss of detail. T/F?

T

The beam thickness or width perpendicular to the scan plane results in ____ artifact; which is often seen as the appearance of false debris in echo-free areas.

Slice/section thickness or Elevation resolution

To confirm or rule out sludge in the gallbladder; the patient should be ____.

Repositioned/turned

For transducer array with one row of elements; acoustic lens can be used to reduce beam section thickness and its effect. T/F?

T

____ artifact is the interference pattern resulting from constructive and destructive interference of echoes returning simultaneously from many scatterers. This artifact makes a gray-scale image appearing ____.

Speckle;Grainy

In order for reverberation artifact to occur; two strong reflectors are required and the transducer can be one of them. T/F?

T

With reverberation artifact; added reflectors are imaged with equal separation. T/F?

T

With reverberation artifact; subsequent or added reflections are stronger than previous ones. T/F?

F

____ artifact occurs when there are two strong reflecting interfaces that are close together and parallel to sound beams.

Comet Tail

The front and rear surfaces of an object or structure; such as a BB pellet or an air bubble; act as two strong reflectors to produce reverberation artifact. This is called comet-tail artifact. T/F?

T

Ring-down artifact is a form of _____ artifact.

Reverberation

Ring-down artifact is seen as a column of echoes behind a collection of ____.

Gas

Ring-down artifact is seen as dirty shadows that help improve visualization of structures/organs located deep to the intestine. T/F?

F

Mirror image is commonly seen around the _____.

Diaphragm

When a strong reflector; such as the diaphragm or pleura, is located in the scan plane; _____ artifact is likely to occur.

Mirror

Refraction of light distorts the presentation of structures. T/F?

T

Refraction of sound displaces structures laterally. T/F?

T

Refraction of sound may produce doubling of a single structure. T/F?

T

Additional beams produced by array transducers are called ____ lobes and ____ lobes.

Side; Grating

Additional beams emitted from an array transducer displace structures laterally. T/F?

T

Additional beams emitted from an array transducer are stronger than the main beam and normally produce echoes that are imaged. T/F?

F

_____ artifact occurs when propagation speed of sound is not 1.54 mm/μs.

Speed Error

_____ artifact places structures closer to or further from the surface than they should be.

Speed Error

Speed error artifact misplaces structures axially. T/F?

T

Speed error artifact produces a step-off or broken appearance on the image. T/F?

T

_____ artifact occurs when not all the echoes from one pulse are received before the next pulse is sent.

Range Ambiguity

_____ artifact places structures closer to; but NOT further from; the surface than they should be.

Range Ambiguity

Range ambiguity artifact misplaces structures laterally. T/F?

F

_____; _____; _____; _____; and _____ cause improper location of objects on a display.

Reverberation; Mirror image; Grating lobe; Speed error; Range ambiguity (and Refraction)

_____ and _____ artifacts displace structures axially.

Speed Error; Range Ambiguity

To avoid range ambiguity artifact; _____ must be applied or obeyed.

13 μs/cm rule

Acoustic shadowing and enhancement are descriptions of _____ artifacts.

Attenuation

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

Acoustic Shadowing

Acoustic enhancement is caused by _____ attenuating structure.

Weakly

Gallbladder would likely demonstrate acoustic enhancement. T/F?

T

A gallstone would likely demonstrate acoustic _____.

Shadowing

_____ and _____ spreading cause shadowing posterior to the edges of a circular or oval object and improper location of objects lateral to the circular object. This artifact is called _____.

Refraction; Beam; Edge Shadowing

To confirm or rule out artifacts; such as mirror image; reverberation; refraction; and side & grating lobe; a sonographer should ____.

Change patient position; Change scanning window/approach

Gray-scale artifacts include aliasing. T/F?

F

The most common artifact encountered in Doppler ultrasound is _____.

Aliasing

Spectral aliasing is the appearance of Doppler information on the _____ of the baseline.

Wrong

Aliasing occurs when the Doppler shift frequency has exceeded the aliasing or Nyquist limit. T/F?

T

Nyquist limit is equal to half of the Doppler PRF. T/F?

T

Aliasing will occur when the Doppler shift frequency is greater than _____ of the Doppler PRF.

1/2

Increasing PRF is a method of eliminating aliasing. T/F?

T

Shifting the baseline is a method of eliminating aliasing. T/F?

T

Increasing Doppler angle is a method of eliminating aliasing. T/F?

T

Increasing transducer frequency is a method of eliminating aliasing. T/F?

F

Switching to continuous wave Doppler is a method of eliminating aliasing. T/F?

T

Aliasing does NOT occur in continuous wave Doppler. T/F?

T

_____ PRF causes range ambiguity in spectral Doppler.

High

Decreasing PRF decreases the likelihood of range ambiguity artifact in spectral Doppler. T/F?

T

Range ambiguity produces _____ gate location in spectral Doppler studies.

Wrong

In spectral Doppler; solving aliasing by decreasing operating frequency increases the possibility of range ambiguity artifact. T/F?

T

When spectral Doppler gain is set too high; _____ artifact is likely to occur.

Spectral Mirror Image

When Doppler angle is at or near 90 degrees; _____ artifact is likely to occur.

Spectral Mirror Image

Cross talk is a(n) _____ duplication of spectral Doppler signal.

Electronic

Cross talk occurs when receiver (spectral Doppler) _____ is set too high.

Gain

With Doppler imaging; artifact caused by heart or vessel wall motion is called _____.

Clutter

_____ wall filter causes missing spectral Doppler information on the display.

High

Artifacts seen with color Doppler imaging are aliasing; mirror image; shadowing; clutter; noise; and twinkle. T/F?

T

With color Doppler imaging; _____ artifact occurs when the mean Doppler shift exceeds the Nyquist limit.

Aliasing

With color Doppler imaging; ____ artifact is seen as color from the opposite extreme or side of the color map showing up in the vessel.

Aliasing

With color Doppler imaging; _____ artifact occurs when an image of a vessel is duplicated on the opposite side of a strong reflector; such as the pleura or diaphragm.

Mirror Image

With color Doppler imaging; _____ artifact occurs when there is lack of color seen posterior to a highly attenuating structure; such as calcified plaque.

Shadowing

With color Doppler imaging; _____ artifact results from tissue; heart wall or valve; or vessel wall motion; causing color to be seen.

Clutter/Ghosting/Flash

Clutter is also call _____ or _____ artifact.

Ghosting; Flash

With color Doppler imaging; _____ artifact is seen behind a strongly reflecting scattering or rough surface of a small gallstone; renal stone; etc.

Twinkle

With color Doppler imaging; _____ artifact is seen as color bleeding into or showing in area of gray-scale or of no motion due to high sensitivity setting.

Blooming

High color Doppler _____ can cause blooming artifact.

Gain

Color _____ is an artifact that appears as color in area where there is tissue vibration caused by turbulence distal to a severe stenosis.

Bruit

Power Doppler imaging is more sensitive to motion of transduce; patient; or tissue; therefore; it is more likely to show ____ artifact.

Clutter/Ghosting/Flash