CH7 - Artifacts - Multiple Choice

Which best defines an "artifact" in ultrasound imaging? A) Not a true representation of anatomy B) Caused by patient motion C) Enhanced by TGC settings D) A normal soft tissue echo pattern

A) Not a true representation of anatomy

Which of the following is NOT one of the six ways an artifact can be improper? A) Missing B) Improper shape C) Overly attenuated D) Misplaced

C) Overly attenuated

Why must sonographers recognize image artifacts? A) To shorten exam time B) To reduce interpretive errors C) To calibrate the TGC D) To increase the frame rate

B) To reduce interpretive errors

Artifacts are classified according to what? A) Patient body habitus B) Transducer frequency C) Current FDA guidelines D) The causative mechanism

D) The causative mechanism

What are the two major artifact classification groups? A) Reflection & Refraction B) Axial & Lateral C) Reverberation & Enhancement D) Propagation & Attenuation

D) Propagation & Attenuation

Which is a Propagation group artifact? A) Enhancement B) Ring-down C) Shadowing D) Focal zone

B) Ring-down

Which is an Attenuation group artifact? A) Enhancement B) Comet tail C) Grating lobes D) Slice-thickness

A) Enhancement

What causes reverberation artifacts? A) Refraction B) Beam divergence C) Multiple reflections D) TGC misadjustment

C) Multiple reflections

What is the most common type of image artifact? A) Enhancement B) Reverberation C) Shadowing D) Speckle

B) Reverberation

Which is NOT one of the four types of reverberation? A) Ring down B) Comet tail C) Mirror artifact D) Grating lobe

D) Grating lobe

When does ring-down artifact occur? A) The beam diverges rapidly B) Tissue attenuation is unusually high C) Two strong reflectors lying parallel D) PRF is set too low

C) Two strong reflectors lying parallel

Which is a classic example causing ring-down artifact? A) Transducer face-skin surface B) Liver-kidney interface C) Diaphragm-lung interface D) Bladder-uterus interface

A) Transducer face-skin surface

In ring-down, which signal is real? A) The second signal B) All signals equally C) The first signal D) None of the signals

C) The first signal

What happens to intensity of each subsequent ring-down echo? A) It decreases each time B) It stays constant C) It fluctuates randomly D) It increases each time

A) It decreases each time

How are ring-down artifact echoes spaced on the image? A) Randomly scattered echoes B) Exponentially increasing distance C) They appear only once D) Equal spacing matching the reflectors

D) Equal spacing matching the reflectors

How does depth of the first ring-down echo compare to the real echo? A) Same depth as the real echo B) Twice the distance of the real echo C) Half the distance of the real echo D) Unrelated to the real echo depth

B) Twice the distance of the real echo

How does ring-down reverberation appear on the image? A) Linear echoes of decreasing intensity B) A single bright dot near the transducer C) Irregular scattered echo dots D) A black shadow beneath the structure

A) Linear echoes of decreasing intensity

Why can ring-down only occur with strongly reflecting surfaces? A) Weak reflectors move too fast B) Weak reflectors absorb sound instantly C) Weak reflectors lack sufficient acoustic mismatch D) Weak reflectors are outside the field of view

C) Weak reflectors lack sufficient acoustic mismatch

Can reverberation artifacts be entirely eliminated? A) Yes, with color Doppler B) No, only reduced C) Yes, with higher gain D) No, nothing helps

B) No, only reduced

How can reverberation artifacts be reduced? A) Increasing the overall system gain B) Increasing the PRF C) Adding more focal zones D) Decreasing gain and changing angle

D) Decreasing gain and changing angle

Comet tail is what type of reverberation? A) A directional reverberation B) A type of shadowing C) A type of enhancement D) A non-directional reverberation

D) A non-directional reverberation

What creates a comet tail artifact? A) Large, smooth reflectors B) Tiny, attenuating structures C) Consistently low PRF settings D) Frequent TGC misadjustment

B) Tiny, attenuating structures

Which can cause comet tail artifact? A) Tiny gas bubbles or calcifications B) Bone fragments and gallstones C) Amniotic fluid collections D) Ascites fluid pockets

A) Tiny gas bubbles or calcifications

Why does comet tail resemble a comet's tail? A) Beam divergence at the transducer face B) Refraction bending the ultrasound beam C) Closely spaced echoes from a tiny source D) TGC banding artifacts appear

C) Closely spaced echoes from a tiny source

What causes a multipath reflection artifact? A) Two parallel strong reflectors B) A different path to the reflector C) Beam narrowing at the focus D) PRF being set too low

B) A different path to the reflector

Where is multipath reflection artifact usually positioned? A) Shallower than actual B) At the same depth C) Only laterally displaced D) Deeper than actual

D) Deeper than actual

Why are multipath reflection echoes usually weak? A) They are usually strong instead B) They are unaffected by path length C) Longer path causes higher attenuation D) They are always absent

C) Longer path causes higher attenuation

How can multipath reflection artifact be reduced? A) Changing the interrogation angle B) Increasing the overall gain C) Adding more focal zones D) Increasing the PRF value

A) Changing the interrogation angle

When does mirror image artifact occur? A) Sound interacts with a flat, weak reflector B) Beam frequency is too low C) Sound interacts with a curved specular reflector D) TGC is misadjusted

C) Sound interacts with a curved specular reflector

Which structures classically produce mirror image artifact? A) Bladder wall and diaphragm B) Bone and gas pockets C) Liver and spleen tissue D) Kidney and pancreas

A) Bladder wall and diaphragm

Where does a mirror image appear relative to the real structure? A) Same side, same distance B) At a random location C) Always superficial to the reflector D) Equidistant, opposite side of reflector

D) Equidistant, opposite side of reflector

Which is NOT a method to reduce mirror image artifact? A) Decreasing overall gain B) Increasing PRF C) Changing angle of interrogation D) Partial bladder voiding

B) Increasing PRF

What are side lobes? A) Low intensity beams outside the main beam B) Beams equal in intensity to the main beam C) Beams only in linear array transducers D) Beams from TGC misadjustment

A) Low intensity beams outside the main beam

Side lobe artifact is worse with which transducer? A) Linear array B) Curved array C) Phased array D) Mechanical sector

C) Phased array

How does a side lobe artifact typically form? A) Side lobes interact only with gas B) Side lobes reflect off a curved reflector C) Side lobes result from PRF errors D) Side lobes result from TGC banding

B) Side lobes reflect off a curved reflector

What assumption does the transducer make about returning echoes? A) They came from side lobes B) They are always noise C) They are always real anatomy D) They came from the main beam path

D) They came from the main beam path

Side lobe artifacts appear as lines where relative to the diaphragm? A) Only anterior to the diaphragm B) Only posterior to the diaphragm C) Only lateral to the diaphragm D) Anterior or posterior to the diaphragm

D) Anterior or posterior to the diaphragm

What diffuse artifact can side lobes create near a cystic structure? A) Shadowing in the liver B) Pseudo-sludge from bowel gas C) Mirror image in the bladder D) Comet tail in the spleen

B) Pseudo-sludge from bowel gas

Very low intensity side lobes contribute to what? A) General system noise B) Improved resolution C) TGC calibration D) Increased PRF

A) General system noise

How can side lobe artifacts be reduced? A) Increasing frequency B) Increasing the PRF value C) Adjusting the angle or gain D) Adding more focal zones

C) Adjusting the angle or gain

What are grating lobes? A) Beams weaker than side lobes B) Beams stronger than individual side lobes C) Beams only from single-element transducers D) Beams from TGC misadjustment

B) Beams stronger than individual side lobes

How do grating and side lobes compare to the primary beam? A) Stronger than the primary beam B) Equal to the primary beam C) Unrelated to the primary beam D) Weaker than the primary beam

D) Weaker than the primary beam

When are grating lobe echoes most likely displayed? A) Always, regardless of tissue type B) Only in normally echogenic regions C) Strong reflectors in anechoic regions D) They are never displayed at all

C) Strong reflectors in anechoic regions

How do grating lobe artifacts usually appear? A) In incorrect locations B) In the correct location C) With no visible effect D) Only as generalized noise

A) In incorrect locations

How does grating lobe intensity compare to the correct structure? A) Always much stronger overall B) Always exactly equal C) Weaker, sometimes stronger D) Always completely absent

C) Weaker, sometimes stronger

What composite speed of sound do systems assume for soft tissue? A) 1540 m/s B) 1450 m/s C) 1640 m/s D) 1340 m/s

A) 1540 m/s

The system uses assumed speed of sound to do what? A) Calculate transducer frequency B) Calculate PRF C) Set the TGC curve D) Estimate time of flight and depth

D) Estimate time of flight and depth

What causes a speed error (tissue velocity) artifact? A) TGC misadjustment errors B) Velocity differs from 1540 m/s C) PRF set much too low D) Excessive beam divergence issues

B) Velocity differs from 1540 m/s

How does sound speed through a fluid path compare to soft tissue? A) Slower than soft tissue B) Faster than soft tissue C) Equal to soft tissue D) Unpredictable

A) Slower than soft tissue

What effect does a slower fluid path have on posterior echoes? A) They are positioned shallower B) They are unaffected C) They are positioned deeper D) They are removed entirely

C) They are positioned deeper

What artifact can speed error cause in a cyst's posterior wall? A) A visibly thickened wall B) A break in continuity C) Increased brightness D) No noticeable effect

B) A break in continuity

If a cyst is anterior to the diaphragm, what can speed error cause? A) The diaphragm appears intact B) The diaphragm disappears entirely C) The diaphragm appears doubled D) An artifactual break in the diaphragm

D) An artifactual break in the diaphragm

Range ambiguity is specific to what type of ultrasound? A) Continuous wave B) Both equally C) M-mode only D) Pulsed ultrasound

D) Pulsed ultrasound

What causes range ambiguity artifact? A) TGC adjustment level B) Pulse repetition frequency C) Overall gain level D) Transducer frequency

B) Pulse repetition frequency

What is the result of range ambiguity artifact? A) The artifact appears too shallow B) The artifact appears too deep C) The artifact appears at correct depth D) No visible artifact occurs

A) The artifact appears too shallow

What is another name for slice-thickness artifact? A) Axial resolution artifact B) Grating lobe artifact C) Beamwidth artifact D) Ballooning effect

C) Beamwidth artifact

Which coordinate plane represents slice thickness? A) X plane B) Z plane C) Y plane D) None of the planes

B) Z plane

How does the system process echoes across the Z axis? A) Uses only the edge echoes B) Ignores them completely C) Doubles their intensity D) Averages assuming central origin

D) Averages assuming central origin

When does slice-thickness artifact NOT cause a problem? A) When tissue properties differ across the Z plane B) It is always a problem C) Same acoustic properties across the Z plane D) Only in cystic structures

C) Same acoustic properties across the Z plane

What causes the classic gallbladder slice-thickness example? A) Averaging beam edge with adjacent bowel echoes B) The gallbladder disappearing entirely C) The gallbladder appearing doubled D) The gallbladder wall thickening

A) Averaging beam edge with adjacent bowel echoes

Slice-thickness artifact must not be mistaken for what? A) A different type of artifact B) An unrelated TGC error C) A pathological process D) Ordinary acoustic shadowing

C) A pathological process

How can slice-thickness artifact be minimized? A) Centering the scan or reducing gain B) Increasing the PRF value C) Increasing the frequency setting D) Adding more focal zones

A) Centering the scan or reducing gain

What does axial resolution artifact (LARRD) result in? A) Side-by-side reflectors not resolved B) Reflectors resolved perfectly C) Increased echo brightness D) Parallel reflectors not resolved

D) Parallel reflectors not resolved

Axial resolution artifact is caused by what? A) Pulse width B) Pulse length C) Cycle width D) PRF

B) Pulse length

What does lateral resolution artifact (LATA) result in? A) Side-by-side reflectors not resolved B) Reflectors parallel to the beam not resolved C) Improved resolution D) Increased shadowing

A) Side-by-side reflectors not resolved

Lateral resolution artifact is caused by what? A) Pulse length duration B) PRF value settings C) Pulse width or cycle width D) TGC curve settings

C) Pulse width or cycle width

Is speckle technically classified as an artifact? A) Yes, always B) No C) Only in color Doppler D) Only in M-mode

B) No

What causes speckle? A) Tissue texture pattern directly B) TGC misadjustment errors C) Excess beam divergence D) Interference from scatterers

D) Interference from scatterers

What is another name for signal amplification artifact? A) Comet tail effect B) Mirror effect C) Ring-down effect D) Ballooning effect

D) Ballooning effect

What causes signal amplification (ballooning) artifact? A) A small acoustic mismatch B) A very large acoustic mismatch C) Low PRF settings D) TGC banding artifacts

B) A very large acoustic mismatch

What is the classic example of signal amplification artifact? A) A gallbladder surrounded by ascites B) A bladder surrounded by bowel gas C) A kidney surrounded by fat D) A liver surrounded by lung

A) A gallbladder surrounded by ascites

Signal amplification must not be mistaken for what? A) A simple fluid cyst B) A calcified gallstone C) A pathologically thick wall D) Ordinary shadowing

C) A pathologically thick wall

How can signal amplification effect be controlled? A) Increasing gain B) Reducing overall gain C) Increasing PRF D) Adding more focal zones

B) Reducing overall gain

Where does electronic noise come from? A) Only from patient motion B) Only from TGC misadjustment C) Only from PRF errors D) Inherent in the system itself

D) Inherent in the system itself

How does electronic noise appear on the image? A) As a bright band B) As a black shadow C) As a low-level "haze" D) As linear echoes

C) As a low-level "haze"

How can electronic noise be minimized? A) Decreasing overall gain B) Increasing gain C) Increasing PRF D) Increasing frequency

A) Decreasing overall gain

How should the TGC be set to avoid artifact? A) As steep abrupt spikes B) As a completely flat line C) In a subtle, graded curve D) In a fully random pattern

C) In a subtle, graded curve

What creates a TGC banding artifact? A) A misaligned TGC slide pot B) Increasing overall gain C) Decreasing PRF D) Changing transducer frequency

A) A misaligned TGC slide pot

What is a banding artifact? A) An area of complete signal loss B) A black shadow C) A bright halo D) A band of altered echogenicity

D) A band of altered echogenicity

Banding artifacts are dangerous because they can do what? A) Improve overall resolution B) Mimic or camouflage a lesion C) Increase the frame rate D) Reduce background noise

B) Mimic or camouflage a lesion

What are the two categories of scanning techniques to overcome artifact? A) System controls and sound interaction B) Increasing and decreasing frequency C) M-mode and B-mode D) Linear and curved array use

A) System controls and sound interaction

Which is an example of manipulating system controls? A) Patient body positioning B) Changing probe position C) Focal location, power, gain, TGC D) Patient breathing pattern

C) Focal location, power, gain, TGC

Which is an example of manipulating sound-tissue interaction? A) TGC adjustment settings B) Interrogation angle or position C) Output power adjustment level D) Focal zone number count

B) Interrogation angle or position

What is another name for enhancement artifact? A) The classic ballooning effect B) A typical comet tail artifact C) A typical ring-down artifact D) Acoustic through-transmission

D) Acoustic through-transmission

What is the purpose of TGC regarding tissue depth? A) To increase image resolution B) To reduce the PRF value C) To eliminate all side lobes D) Graded amplification with depth

D) Graded amplification with depth

What causes enhancement (through transmission) artifact? A) Sound attenuates more through fluid than soft tissue B) Sound attenuates less through fluid than soft tissue C) Sound speed increases in fluid D) Sound frequency decreases in fluid

B) Sound attenuates less through fluid than soft tissue

Why does enhancement artifact occur despite TGC compensation? A) TGC compensates strictly by distance B) TGC compensates based on tissue type C) TGC ignores fluid paths entirely D) TGC turns off automatically in fluid

A) TGC compensates strictly by distance

How does enhancement artifact appear on the image? A) A dark band posterior to the cyst B) No visible change C) A bright band behind the cyst D) Lateral shadowing

C) A bright band behind the cyst

Enhancement artifact is clinically useful for what? A) Identifying a solid mass B) Identifying a cystic structure C) Identifying bone tissue D) Identifying gas pockets

B) Identifying a cystic structure

What determines the brightness of posterior enhancement? A) The overall width of the cyst B) The transducer frequency used C) The PRF value setting D) The length of the fluid path

D) The length of the fluid path

Besides fluid, what other tissue can produce posterior enhancement? A) Dense cortical bone tissue B) A small calcified nodule C) Fibroadenoma or liver mass D) Trapped bowel gas pockets

C) Fibroadenoma or liver mass

What two interactions cause edge effect artifact? A) Refraction and internal reflection B) Reverberation and shadowing C) Enhancement and speckle D) Grating lobes and side lobes

A) Refraction and internal reflection

When does refraction-based edge effect occur? A) Sound strikes perpendicular with equal velocities B) Sound strikes a flat, weak reflector C) Sound strikes obliquely where velocities differ D) PRF is too high

C) Sound strikes obliquely where velocities differ

What is the result of refraction at a curved edge? A) Beam bends, shadowing distal to it B) Enhancement occurs posterior to it C) No visible effect occurs at all D) Increased brightness is seen

A) Beam bends, shadowing distal to it

Which structures classically show refraction edge effect? A) Bone and gallstones B) Diaphragm and lung C) Amniotic fluid and fetal skull D) Cysts and the gallbladder

D) Cysts and the gallbladder

Where does total internal reflection edge effect occur? A) At flat interfaces with low mismatch B) Curved edges, low-to-high velocity C) Only in cystic structures D) Only with gas

B) Curved edges, low-to-high velocity

What is the result of total internal reflection at a curved edge? A) Shadowing distal to the reflection point B) Enhancement distal to the interface C) No visible effect D) A duplicated mirror image

A) Shadowing distal to the reflection point

What is the classic example of total internal reflection edge effect? A) The gallbladder wall edge B) The liver capsule surface C) Amniotic fluid and fetal skull D) The bladder wall surface

C) Amniotic fluid and fetal skull

Acoustic shadowing occurs when the beam interacts with what? A) A low-attenuating structure B) A highly attenuating structure C) Fluid only D) Soft tissue only

B) A highly attenuating structure

By what mechanisms can acoustic shadowing occur? A) TGC misadjustment error B) A sudden PRF change C) An unexpected frequency shift D) Absorption, reflection, refraction

D) Absorption, reflection, refraction