ECHO 2013 / Artifacts of Imaging and Doppler Know Your Physics
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3D Artifacts: MVR
LA side of MVR |
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Reverberation and Acoustic |
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Shadowing Artifacts in 3D |
LV side of MVR |
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Reverberation Artifacts
Slight change in imaging plane
Refraction Artifact
Ultrasound Property
An oblique ultrasound beam is refracted when it reaches a surface of different impedances
The refracted beam can be reflected back to the transducer
The transducer places the refractedRefractor image along the beam path
•Refraction Artifact
–Echoes formed from a refracted beam which places a duplicate of the real anatomic structure on the image (typically next to structure)
Artifact |
Real |
Artifact |
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• Correction: |
ASSUMPTIONS: |
– Change acoustic window |
•Sound travels in a straight line |
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•Echoes originate from objects |
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in the path of the US beam |
Refraction Artifact
Refractor: Rib
Mirror Image Artifact
•Ultrasound property
–Sound bounces off a strong reflector (ie: diaphragm) in the direct path of the US beam but which is not perpendicular
–The structure acts like a mirror and reflects the US beam laterally to second reflector which returns the beam to the transducer
–The final reflected US pulse returns to the transducer which thinks the sound is coming from another reflector in its path
Mirror Artifact
The ―mirror‖ image (white arrow) is created deeper than the true anatomic structure
Motion will be in the opposite direction
Correction
Change acoustic window
Classic Mirror Image Artifact
ASSUMPTIONS:
•Sound travels in a straight line
•Echoes originate from objects in the path of the US beam
Artifact?
Multipath Image
Of the Mitral Valve
TEE: Deep Gastric View, AVR
Indication: Rule out endocarditis
Clues to Artifact What Type of Artifact:
• Motion identical to another real structure |
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Structure deeper |
– amplitude and frequency at a multiple of the |
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Motion opposite |
real structure |
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• Not reproduced in an orthogonal or other view
Mirror Doppler Artifact
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Note: Flow appears to |
• Ultrasound property |
be AWAY from |
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–Sound bounces off a strong reflector which acts like a mirror and reflects the US beam laterally to second reflector which returns the beam to the transducer
–The final reflected US pulse returns to the transducer which thinks the sound is coming from another reflector in its path
Eiselat F et al. J Am Soc Echocardiogr 2006;19:1191.e1-1191.e3.)
Mirror Doppler Artifact
•Ejection time same as AS
•Velocity lower and related to the difference in angle of insonation
•Doppler mirror image artifacts usually occur adjacent to highly reflecting acoustic interfaces such as metallic surfaces (eg, prosthetic valves) or the wall of great arteries.
Eiselat F et al. J Am Soc Echocardiogr 2006;19:1191.e1-1191.e3.)
Propagation Path Artifact: Grating and
SideLobes
Ultrasound Property
Extraneous beams of ultrasound are generated from the edges of individual elements
Grating lobes are the result of the summation of side lobes from
individual crystals.
• Side Lobes
– more prominent with phased array transducers
–weaker signals than from “real” echoes appear lateral to the object