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Artifacts Flashcards

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1
Q

Name three Resolution artifacts

A
  1. Poor axial resolution
  2. Poor lateral resolution
  3. Poor elevational resolution (slice thickness)
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2
Q

What is an axial resolution artifact?

A

When two reflectors at different depths appear as one structure

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3
Q

How does poor axial resolution artifact appears or most noticeable ?

A

Most noticeable when:

Low frequency transducer

Long pulse length

Reflectors are very close in depth

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4
Q

✅ How to fix / improve axial resolution artifact?

A

Increase frequency

Increase damping

Use shorter pulse length

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5
Q

Is poor axial resolution artifact affected by depth & focus?

A

NO

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6
Q

Axial resoulution formula

A

Axial resolution = SPL
________________
2

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7
Q

What is a lateral resolution artifact and how is it caused?

A

When two side-by-side reflectors appear as one on the image, cause by wide ultrasound beam width.

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8
Q

How does lateral resolution artifact appears on the image?

A

Side-by-side structures look merged

Borders appear blurred or widened

Small structures look thicker than they really are

More common in the near field and far field

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9
Q

4 ways to fix or improve lateral resolution artifact

A
  1. Increase frequency
  2. Use proper focusing (place focal zone at the structure)
  3. Increase aperture size
  4. Use multiple focal zones
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10
Q

What is it Elevational resolution artifact and how is it caused?

A

When echoes from above or below the imaging plane are displayed as if they are in the scan plane.

Caused:
Thick ultrasound beam

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11
Q

How does an elevational‑resolution artifact appear on an ultrasound image, and what is a classic example of this artifact?

A

False internal echoes inside fluid-filled structures

Commonly seen in fluid-filled structures.

Example :
Cyst may apper to have internal flase echoes even thought its truly anechoic (black).

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12
Q

How to fix or reduce elevational resolution artifact ?

A

it can only be reduce by narrowing the slice thickness.

use 1.5D/2D array transducer.

Use higher frequency (thinner beam)

Optimize transducer position (scan from multiple angles)

Use spatial compounding (averages out-of-plane echoes)

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13
Q

what are the 3 artifact that are cause by sound change?

A
  1. Refraction
  2. Mirror Artifact
  3. Multi-path Artifact
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14
Q

what are the the 4 artifacts that are cause by sound that didn’t return directly to the transducer

A
  1. Reverberation
  2. Ring down / comet tail
  3. Mirror artifact
  4. Multi-path artifact
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15
Q

what are the 2 artifact that are cause by sound energy from outside of the main beam interacted with reflectors?

A
  1. Grating / side lobes
  2. slice thickness
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16
Q

what are the 2 artifacts that are cause by propagation speed issues?

A
  1. Speed Error artifact
  2. Range Ambiguity artifact
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17
Q

“What is the Refraction image artifact, and what causes it?”

A

What it is:
Lateral displacement & duplication of a structure, aka 2nd image

Cause:
Sound beam bends when crossing tissues with different propagation speeds at an oblique incidence

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18
Q

“How does Refraction artifact appear on ultrasound, where is it most commonly seen, is ti fixable?

A

Appearance:
* Side-by-side duplication
* Structure shifted laterally

Seen in:
* Abdomen
* Cysts
* Rectus abdominis
* Gallbladder

Fixable? ❌ No
Reduce: change angle

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19
Q

“What is the mirror image artifact, and what causes it?”

A

What it is:
Duplicate structure displayed

Cause:
strong reflector & indirect path

Sound beam hits strong relfector, bounces back & forth , returns late and makes duplicated image deeper (diaphragm).

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20
Q

“How does Mirror Image artifact appear on ultrasound, where is it most commonly seen and is it fixable

A

Appearance:
* second / duplicate stucture
* displayed deeper

Seen in:
* liver over the diaphragm
* kidney
Liver mirrored above diaphragm
* Duplicate vessel in Doppler
* Lung/diaphragm interfaces
* Strong specular reflectors

— it can appear in:
* Gray scale
* Color Doppler

Fixable? ❌ No

Reduce:
- change angle only
- Change windpw
- Lower gain

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21
Q

What is Multi-path artifact and what cause it?

A

What it is:
Structure displayed at incorrect depth

Cause:
The beam hits/ boundce off a surface, changes direction, takes a longer path, returns late at depper depth.

the echo takes a detour instead of coming straight back.

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22
Q

“How does Mulitpath artifact appear on ultrasound, where is it most commonly seen and is it fixable

A

Appearance:
* Misplaced echoes are placed in wrong location .

🔑 results in subtle nonspecific changes

  • false, shadowy, or “ghost” images structures are incorrectly displayed as being deeper than their true location.

Seen in:
* Near ribs
* Diaphragm

Fixable? ⚠️ Partially

Reduce:
change angle/window
repostion patient

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23
Q

What is Speed Error artifact and what causes it ?

A

What it is:
Incorrect depth placement

Cause:
System assumes sound speed = 1540 m/s
Actual tissue speed differs

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24
Q

“How does Speed Error artifact appear on ultrasound, where is it most commonly seen and is it fixable?

A

Appearance:
* Structure appears too deep or shallow

  • Going to make anatomy appear almost broken, step-off from itself or displace ,cut off ,split

Seen in:
* Fat
* Silicone implants

Fix ?
No ❌ Cannot be corrected

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25
What is Range Ambiguity artifact and what casues it ?
What it is: Reflectors or structures are located deeper and the Echo assigned to wrong depth Cause: PRF too high → echo returns after next pulse ## Footnote The machine thinks an echo came from a shallow depth when it actually came from deeper. PRF too high → echoes don’t return in time → machine places them too shallow.”
26
“How does Range Ambiguity artifact appear on ultrasound, where is it most commonly seen and is it fixable?
Appearance: * Structure displayed too shallow Seen in: * Deep imaging * Pulsed Doppler Fixable? ✅ Yes Fix: ✅ Lower PRF ✅ Increase depth
27
What is Reverberation artifiact and what causes it?
What it is: Multiple equally spaced echoes Cause: Sound trapped between two strong reflectors
28
“How does reverberation artifact appear on ultrasound, where is it most commonly seen and is it fixable?
Appearance: * Parallel horizontal lines * intensity decrease with depth * ladder pattern.” Seen in Lung (A-lines) Near pleural line * Metallic objects / needles, clips * Calcification * Catheters * Diaphragm * Vessel walls Fixable? ❌ Not truly Reduce: change angle, harmonics help Lower gain
29
“What is the Ring-down artifact, and what causes it?”
What it is: A bright, continuous vertical line caused by resonance of trapped gas bubbles. Cause: Gas bubbles vibrate aka (resonate) ## Footnote Memory line: “Gas vibrates → continuous streak.”
30
How does Ring-Down artifact appear on ultrasound, where is it most commonly seen and is it fixable?
Appearance: * Solid vertical bright line * Parallel to the sound beam Continuous — not spaced * No gaps between echoes * Does NOT fade like reverber Seen in: Gas collections * Air in biliary system (pneumobilia) * air in lungs * Air in abscesses * Bowel gas Fixable? ❌ No Reduce: change angle only
31
How does comet Tail artifact appear on ultrasound, and where is it most commonly seen?” and can it be fixed?
Appearance: Solid hyperechoic line Extends deep from reflector No spacing between echoes Tail-like appearance Parallel to beam axis Narrow bright trail Commonly seen: 🔹 Mechanical / prosthetic heart valves (high propagation speed material) 🔹 Metal 🔹 Surgical clips 🔹 Calcifications 🔹 Gas bubbles (resonance vibration) Fixable? ❌ No Reduce: change angle only
31
What is Comet Tail artifact and what causes it?
What: Reverberation echoes are so close together they blend/ merge into one bright vertical line extending downwards. Cause: closely spaced reflectors → echos Bouncing repeatedly back-and-forth.
32
What is a lobe artifact and what causes it?
Lobe artifact occurs when sound energy travels outside the main beam axis (side or grating lobes). If a strong reflector is hit by this off-axis beam, the system assumes the echo came from the main beam → places it incorrectly on the image. Cause: Off-axis beam energy
33
How does Lobe artifact appear on ultrasound and it it fixable ?
Appearance: ⭐ Characteristics of Lobe Artifact: * Second copy of the true reflector * side by side * Same depth * off-axis beam * degrades lateral resolution fix: yes ✅ Tissue Harmonic Imaging ✅ Apodization ✅ Subdicing ✅ Spatial Compounding
34
What is the Shadowing artifact, and what causes it?”
What it is: Shadowing is a dark ( hypoechoic or anechoic ) region that appears below a highly attenuation structure. Cause: High attenuation or reflection * Attenuation is higher in the tissue above the shadow
35
How does Shadowing artifact appear on ultrasound, where is it most commonly seen and is if fixable?
Appearance: * Anechoic or Hypoechoic shadow behind /(Distal) object * No echos behind the sturture Seen in: * Bone * Calcifications * Stones * Gallstone/ kidney stone * fibous tissue Fixable? ❌ No (physics) Reduce: change angle, window, lower frequency Increase outpower (sometines help)
36
What is the Edge Shadowing artifact, and what causes it?”
What it is: A dark shadow appears at the edges of a curved structure because the beam bends (refracts) and spreads out. Cause: ✅ Occurs at the edge of a curved structure, The beam refracts -bends at the edge. ✅ Beam diverges (spreads-out ) ✅ cause intensity to drop → Not enough sound continues → dark edge shadow ⭐ SPI trigger words: curved reflector + refraction + divergence
37
“How does edge shadowing artifact appear on ultrasound, where is it most commonly seen, and how can it be fixed or improved?
Appearance: ✅ Dark Hypoechoic ✅ Extends downward from the sides ✅ Same color as background ✅ Can hide side anatomy Seen in: - Cysts - Rounded masses - Testicle edge - Breast implant edge - Any curved fluid sturctures fixed? NO, it cant be fixed - change angel (might help)
38
What is the Enhancement artifact, and what causes it?”
What it is: a bright (hyperechoic) area that appears deeper than a structure with LOW attenuation. * Structure lets sound pass easily → deeper echoes look brighter than normal. Cause: abnormally Low attenuation - Low attenutation structures ## Footnote hyperechoic is bright white area
39
How does Enhancement appear on ultrasound, where is it most commonly seen and can it be fixed?
Appearance: * Hyperechoic region beneath tissues with abnormally low attenuation - return echoes are strong which cause brighter echo below Seen in: * Cysts * Fluid * Bladder * Blood vessels *Gallbladder fix: NO, it can't be fixed
40
What is the Focal Enhancement artifact, and what causes it?”
What it is: A bright horizontal (side-to-side) band at the depth of the focal zone. Cause: Maximum/increase beam intensity at focus
41
How does Focal Enhancement artifact appear on ultrasound, and where is it most commonly seen?”
Appearance: *Bright horizontal band *Side-to-side brightness * Same depth across image *Uniform bright strip *Looks like TGC band error *Located at focus marker depth Seen in: * Focal zone
42
How is Focal Enhancement fix or improved?
✅ ( we this in PLAX view) - Adjust focus depth -Move focal zone -Reduce number of focal zones
43
What is the Aliasing artifact, and what causes it?
What it is: Velocity wrap-around Cause: PRF too low (Nyquist limit exceeded)
44
How does Aliasing artifact appear on ultrasound, where is it most commonly seen and how is it fixed ?
Appearance: * Color reversal * Spectral wrap Seen in: * Color Doppler * PW Doppler How to fix: ✅ Increase PRF ✅ Shift baseline ✅ Lower transmit frequency ✅ Use CW Doppler
45
What is the Crosstalk artifact, and what causes it?
What it is: Signal appears on both sides of baseline Cause: Excessive Doppler gain
46
How does Crosstalk artifact appear on ultrasound, where is it most commonly seen and how can it be fixed?
Appearance: * Mirrored waveform Seen in: * Spectral Doppler Fix: ✅ Reduce Doppler gain
47
What is the Flash artifact, and what causes it?
What it is: Random bust of color that appears over the tissue (not ture blood) because the system detects motion/ movement Cause: Motion during color doppler sampling (probe or patient) - patient movement - Tissue or vessles wall motion - cardiac movement
48
How does Flash artifact appear on ultrasound, where is it most commonly seen and what are the 5 steps to fix it
Appearance: - Random color speckle or over tissue - Looks like flow but doesn’t follow a vessel Seen in: * Color Doppler **Fix:** 1. Stabilize the probe / ask patient to hold breath 2. Decrease color gain 3. Increase wall filter 4. Lower color sensitivity (reduce 5. Decrease color box size (helps frame rate + reduces motion effects)
49
What is the Speckle artifact, and how is it fixed?
Cause: Interference of echoes Fix: Spatial compounding]
50
What is the Noise artifact, cause, apperacance and how is it fixed?
random speckle/static signals on the image or Doppler that are not real echoes, usually from low signal (low amplication echoes) Cause: ✅ Low signal-to-noise ratio ✅ Gain set too high ✅ Weak returning echoes being over-amplified Fix: Adjust gain / filters ✅ Where It Appears **in gray scale**: * grainy background * salt-and-pepper look **in Doppler: ** * random spectral spikes * color outside vessels fix by : 1. 👉 Decrease gain This is the #1 test answer. 2. Increase output power 3. lower frequency 4. Adjust TGC 5. Adjust Doppler wall filter (for Doppler noise
51
Side lobes artifact come what type of transducer and probe type
Transducer: Single crystal probe Probe type: Mechanical
52
Grating Lobes artifact come from what type transducer and name probe type
Stabilize the probe / ask patient to hold breath Decrease color gain Increase wall filter Lower color sensitivity (reduce persistence / reduce packet size on some machines) Reduce color box size (helps frame rate + reduces motion effects)
53
Side lobes name the transducer and probe type comes from
Transducer: Signal crystal Probe type: Mechanical
54
Grating lobes name the transducer and probe type it comes from
Transducer: Array Probe type: Linear/ phased
55
Temporal Resolution Artifact — What Makes It an Artifact and how does it appear?
Problem: * Frame rate too low Appears: - Motion appears blurred jumpy - Moving reflector placed inaccurately SPI wording: Poor positioning of moving reflectors
56
How To Improve Temporal Resolution
Increase frame rate by: Decrease depth ✅ Narrow sector width ✅ Reduce line density ✅ Use fewer focal zones ✅
57
Spatial Resolution Artifact — What Makes It an Artifact
Problem: Line density too low / resolution too poor Result: Image lacks detail Small structures not separated Objects blur together Again → image not accurate → artifact.
58
How to improve Spatial Resolution artifact ?
✅ Increase Line Density ⭐ 🥈 2️⃣ Use Higher Frequency
59
Spatial resolution depends on what type of digital image and how can you improve it ?
depends: pixel density Improve by: ➡️ Increase pixel density
60
Ghosting (Color Doppler) Cause: Fixable?
Cause: motion of probe or tissue Fixable? ✅ Yes Fix: Stabilize probe Reduce color gain Increase wall filter
61
Clutter (Color or Spectral) Cause: Fixable? Fix:
Clutter (Color or Spectral) Cause: low-frequency motion signals (tissue, wall motion) Fixable? ✅ Yes Fix: Increase wall filter ⭐ Reduce gain
62
✅ Pixel / Display Resolution Artifact Cause: Fixable? Fix:
Cause: low pixel density Fixable? ✅ Yes Fix: Increase pixel density More display lines
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