LEC 8 - UTZ ARTIFACTS Flashcards
A structure in an image which does not directly correlate with actual tissue being scanned.
ULTRASOUND ARTIFACTS
Any part of an image does not accurately represent the anatomic structures present within the subject being evaluated
ULTRASOUND ARTIFACTS
Artifacts assume different forms, including:
a. Structures in the image that are not actually present.
b. Objects that should be represented but are missing from the image.
c. Structures which are misregistered on the image.
Commonly occurring artifacts:
a. Reverberation
b. Acoustic shadowing
c. Acoustic enhancement
d. Edge shadowing
e. Side lobe artifact
f. Mirror image artifact
- The production of spurious (false) echoes due to repeated reflections between two interfaces with a high acoustic impedance mismatch.
- REVERBERATION ARTIFACT
Are a form of reverberation artifact that appear as a dense tapering V-shaped trail of echoes beyond strong reflectors.
Comet tail artifacts
Short-range rapid reverberations, which can occur between the walls of a hollow structure or metallic object, produce _.
Comet tail artifacts
Are reverberation echoes similar to comet tail artifacts except that the bright artifactual echoes are displayed in a much longer stream.
Ring-down artifacts
A line of bright continuous echoes is seen deep to a strong reflector.
Ring-down artifacts
To help eliminate reverberation artifact, it may be useful to:
a) Increase the amount of gel used.
b) Use a stand-off pad (such as a commercially produced gel pad or a bag of saline)
c) Reduce the gain.
d) Move the position of the transducer.
- This area appears an area of low amplitude echoes (hypoechoic or anechoic) behind an area of strongly attenuating tissue.
- ACOUSTIC SHADOWING
Some interfaces causing such effects are:
Soft tissue/gas (bowel, lung)
Soft tissue/bone, calcium (ribs, calculi)
Normal tissue/fibrous tissue (scars, ligaments)
Shadows from calcium and bone are usually are echo free
clean
Shadows from gas are often partially filled with reverberations
dirty
This artifact appears as localized area of increased echo amplitude behind an area of low attenuation.
- ACOUSTIC ENHANCEMENT
On a scan it will appear as an area of increased brightness, and can commonly seen distal to the fluid filled structures such as urinary bladder, the gallbladder or a cyst.
- ACOUSTIC ENHANCEMENT
A combination of refraction and reflection occurring at the edges of rounded structures and when the speed of sound is different from that in surrounding tissue will result in an edge shadowing artifact.
- EDGE SHADOWING
This artifact is caused by low energy “side lobes” of the main ultrasound beam.
- SIDE LOBE ARTIFACT
Are usually seen in hypoechoic or echo-free structures and appear as bright and rounded line.
- SIDE LOBE ARTIFACT
These artifacts result in a mirror image of a structure occurring in an ultrasound display. They arise due to specular reflection of the beam at a large smooth interface.
- MIRROR IMAGE ARTIFACT
- Structures displayed twice, with one being a mirror of the other. An area close to a specular reflector will be imaged twice, once by the original ultrasound beam and once by the beam after it has reflected off the specular reflectors.
- MIRROR IMAGE ARTIFACT
- Echoes return along the same path from the reflecting surface, back to the transducer. Because the equipment assumes all echoes arise from a straight beam, the reflected echoes are displayed in a line as if originating from below the specular reflecting surface.
- MIRROR IMAGE ARTIFACT
Example of these are (mirror image artifact):
a) Diaphragm/Lung interface
b) Bladder/Rectum interface, when the rectum is gas filled.
