usg artifacts overview

1. ULTRASOUND - ARTIFACTS

2. ARTIFACTS - GRAY-SCALE
• are echoes that appear on the image but do
not have a true correspondence to an
anatomical structure.

4. REVERBERATION
• Appearance- Multiple equidistantly spaced
linear reflections ; ladder • Physics - parallel
highly reflective surfaces, the echoes generated
from a primary US beam may be repeatedly
reflected back and forth before returning to the
transducer for detection • Prevention –
decrease TGC in the near field. Change the beam
angle/alternative window.

6. RING-DOWN ARTIFACT
• Appearance - A line or series of parallel bands
extending posterior to a gas collection • Physics
- US energy causes resonant vibrations in the air
bubbles • Occurs - Posterior to collections of gas
(eg, pneumobilia, portal venous gas, gas in
abscesses, bowel).

8. COMET-TAIL ARTIFACT
• Appearance - Series of multiple, closely spaced
small bands of echoes .
• Physics - is a form of reverberation ; two reflective
interfaces and therefore the sequential echoes are
closely spaced so that the individual signals are not
perceivable in the image .
• Occurs - surgical clips, copper intrauterine device
• Prevention – decrease TGC in the near field.
Change the beam angle/alternative window.

10. SHADOWING
• Appearance - Dark or hypoechoic band deep
to a highly attenuating structure ; clean
shadowing • Physics - US beam encounters a
tissue that attenuates the sound to a greater
than the surrounding tissue ; the strength of the
beam distal to this structure will be weaker
than in the surrounding field. • Occurs -
Calcified lesions, dense tumors • Prevention –
Image the structure at different angles.

12. DIRTY SHADOWING
• Appearance - Low-level echoes in the shadow
deep to gas • Physics - due to the high degree of
reflection at gas/tissue interfaces.

14. INCREASED THROUGH-TRANSMISSION
/ ENHANCEMENT
• Appearance - Hyperechoic area behind a
structure • Physics - Fluid-containing structures
attenuate the sound much less than the solid
structures • Occurs - Behind fluid-filled
structures and occasionally behind solid lesions
that attenuate sound less than the surrounding
tissue (eg, fibroadenoma). • Prevention –
Reduced with spatial compounding. Automatic
TGC functions.

16. “GHOSTING”
• Appearance - Duplication of a structure or
structures appearing wider on the US image •
Physics - speed of sound varies in different
tissues – fat < fluid . • Sound is refracted &
degree of this change in direction is dependent
on both the angle of the incident US beam and
the difference in velocity of the US beam
between the two media • Prevention – change
the angle.

18. REFRACTIVE SHADOWING (EDGE
ARTIFACT, LATERAL CYSTIC
SHADOWING)
• Appearance - Shadow occurring at the edge of
a curved surface • Physics - Sound waves
encountering a cyst wall or a curved surface at a
tangential angle are scattered and refracted . •
Occurs - Cysts, urinary bladder (appearance of a
defect in the bladder wall), diaphragm; if there
is fluid on either side (appearance of a defect in
the diaphragm). • Prevention – disappears on
changing the angle.

20. SIDE LOBE AND GRATING LOBE
ARTIFACTS
• Appearance - Hyperechoic rounded object
within an anechoic or hypoechoic structure -
urinary bladder or gallbladder lumen • Physics -
In linear array transducers, multiple other low-
amplitude beams project radially at different
angles away from the main-beam axis. These are
termed side lobes. • Occurs - Urinary bladder,
gallbladder, needle biopsy • Grating lobe
artifacts are reduced by using very closely
spaced elements in the array.

22. VOLUME AVERAGING (SECTION
THICKNESS, SLICE THICKNESS)
• Appearance - False sludge or debris within
anechoic cystic structures • Physics - As the
beam propagates away from the transducer, it
narrows gradually until it reaches the focal zone;
it then gradually widens again. • Minimized by
placing the focal zone at the level of the tissue.
Occurs - Urinary bladder, gallbladder, and cysts.

24. MIRROR-IMAGE ARTIFACT
• Appearance - Duplicated structure equidistant
from a strong reflective interface • Physics - The
return of the sound beams is delayed, and
therefore the structures from which these delayed
beams are reflected are displayed at a greater
depth than their true anatomic depth • Occurs -
Diaphragm acts as a strong reflective surface in case
of liver lesions or the liver itself can get duplicated.
• Prevention – scan from a different angle , adjust
the focal zone or TGC at the level of the diaphragm ,
scan from multiple windows.

28. ELECTRICAL INTERFERENCE/SPIKING
• Appearance - Bands of noise • Physics - This
can occur when there is not a dedicated
electrical outlet that is appropriately grounded.

30. SPECKLE
• Appearance - The random granular texture
that obscures anatomy in US images (noise) •
Physics - complex interference of US echoes
made by reflectors spaced closer together than
the US system’s resolution limit . • Reduced
using techniques that reduce noise (i.e, higher-
frequency transducer, real-time compounding,
adaptive post-processing , and harmonic
imaging.

32. ANISOTROPY
• Appearance - Hypoechoic area in a structure •
Physics - transducer’s angle of incidence is not
perpendicular to the structure • Occurs -
Tendons, and to a lesser extent in muscles,
ligaments, and nerves.

34. REFERENCES
• 1. Diagnostic Ultrasound, Carol M Rumack and
others, 4th ed.
• 2.Clinical sonography-a practical guide:Roger C
Sanders, Barbara Hall-Terracciano-5th ed.
• 3. The physics of radiology and imaging.
(Thayalan)
• 4.US Artifacts, https://pubs.rsna.org
• 5.Artifacts in ultrasonography,
https://okean.rs