Artifacts - Brightness Alteration
Brightness Alteration
This type of artifact is characterized by the brightness displayed on the monitor - be attenuation or enhancement. Simply put, something looks brighter than it should, or something looks darker than it should.
Four Two Subtypes will be discussed:
1. Acoustic Enhancement
2. Acoustic Shadowing
3. Edge Shadowing
4. Focal Enhancement (aka. Banding)
Four Two Subtypes will be discussed:
1. Acoustic Enhancement
2. Acoustic Shadowing
3. Edge Shadowing
4. Focal Enhancement (aka. Banding)
1. Acoustic Enhancement:
amplification in echo intensity for structures distal to weaker attenuating objects, therefore the region distal to the latter appears more echoic (brighter) than expected.
As per this animation, if B has lesser attenuating property than A, a hyperechoic enhancement will be produced distal to B.
As per this animation, if B has lesser attenuating property than A, a hyperechoic enhancement will be produced distal to B.
2. Acoustic Shadowing:
reduction in echo intensity for structures distal to strongly attenuating objects, therefore the region distal to the latter appears less echoic (darker) than expected.
As per this animation, if B has greater attenuating property than A, a hypoechoic or anechoic shadow will be produced distal to B.
As per this animation, if B has greater attenuating property than A, a hypoechoic or anechoic shadow will be produced distal to B.
3. Edge Shadowing:
when a pulse strikes a high reflective curved edge at a critical angle where all sound is refracted and none reflected, no echo will return to the transducer from that line of sight, so an anechoic region is produced originating from at the edge of the curved reflective structure.
This occurs at vessels, breast cysts, edge of gall bladder, and edge of muscle fascia/ligament.
This occurs at vessels, breast cysts, edge of gall bladder, and edge of muscle fascia/ligament.
The Edge Shadow artifacts are outlined for you in red dotted lines. This image shows the shadow flanks the reflective curvature of the carotid artery.
This can, also, been seen at other vessels, breast cysts, edge of gall bladder, and edge of muscle fascia/ligament.
This can, also, been seen at other vessels, breast cysts, edge of gall bladder, and edge of muscle fascia/ligament.
4. Focal Enhancement (aka. Banding):
characterized by an increase in the intensity of structures – an entire horizontal region (band-like) of tissue appears more hyperechoic - at/around the focal zone.
It looks as if the TGC is increased at the Focal Zone.
At the Focal Zone, the beam profile's intensity is the highest, therefore the amplitude of the echos at this region will, also, be relatively higher than the Near and Far Field. As a result, the brighter image at this segment in comparison to the other depths.
Attenuate/Mitigate: Compound Imaging Off; reduce TGC at the enhanced region
It looks as if the TGC is increased at the Focal Zone.
At the Focal Zone, the beam profile's intensity is the highest, therefore the amplitude of the echos at this region will, also, be relatively higher than the Near and Far Field. As a result, the brighter image at this segment in comparison to the other depths.
Attenuate/Mitigate: Compound Imaging Off; reduce TGC at the enhanced region
Take Home Messages:
- Acoustic enhancement and shadowing can be used to help infer the composition of structures creating the artifact
- Most of the time, for the purposes of Internal Medicine PoCUS indications, these artifacts will not be troublesome, or be of major clinical significance