Learning objectives
- To recognize these artifacts in ultrasound.
- To learn the physical basis that support in order to discriminate them.
- To guide the possible underlying pathology thanks to the correct interpretation of these artifacts.
Background
From the standpoint of radiologic imaging,
we can define the term artifact as an image we cannot correlate with real anatomical structures.
In ultrasound,
artifacts can produce structures that appear in the image but they are not present anatomically,
although structures which are present anatomically may be completely absent.
But that is not all,
because artifacts can even show structures that are present but incorrect in location.
In our daily practice it is very usual to find them,
and we can say they are a...
Imaging findings OR Procedure details
COMET TAIL ARTIFACT
We can consider this phenomenon as a form of reverberation:
We assume that sounds travels in a straight line,
at constant speed.
Therefore,
we can determinate the origin of an echo that goes back if we quantify the time it takes to return.
In the presence of two reflective interfaces,
the echoes generated from the main beam may be repeatedly reflected,
in repeated trips before go back to the transducer,
where they may be detected.
Each echo is received erroneously transcribed as...
Conclusion
Comet tail and Ring-Down artifact usually are used as synonyms,
due to their similar appearance on ultrasound.
But their physical basis are completely different and the mechanism that produce them:
- Comet tail artifact is a form of reverberation; therefore it has the same production basis,
i.e,
repeated trips between the transducer and two reflective surfaces.
- Ring-down artifact occurs when the ultrasound beam excites the liquid trapped between gas bubbles,
producing the liquid to vibrate or resonate.
- Metallic elements/calcifications cause comet tail artifact,...
References
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Feldman M,
Katyal S,
Blackwood M.
Radiographics 2009; 29: 1179-1189.
- Talegón Meléndez A,
Molina Chacón J.
Imagen por Ecografía.
En: JL del Cura,
S Pedraza,
A Gayete.
Radiología Esencial.
Madrid: Editorial Médica Panamericana; 2010.
p.
35-47.
- Física práctica.
En: Middleton,
Kurtz,
Hertzberg.
Ecografía.
Madrid: Marbán; 2007.
p.3-27.
- Duplication Images in vascular sonography.
Rubin J,
Gao J,
Hetel K,
Min R.
J Ultrasound Med 2010; 29: 1385-1390.
- Is it real or is it an artifact.
Keogh C,
Coopberg P....