What is the difference between comet-tail and ring down artifact?
Penelope Carter
Updated on June 17, 2026
Comet-tail artifacts can be seen in normal and abnormal lungs and are described in more detail in Chapter 9 . Ring-down artifact is similar to comet-tail artifact but is produced by a different mechanism ( Figure 6.3 ). The source of ring-down artifact is a small pocket of fluid trapped by surrounding air bubbles.
What does artifact mean on ultrasound?
Artifacts are any alterations in the image which do not represent an actual image of the examined area. They may be produced by technical imaging errors or result from the complex interaction of the ultrasound with biological tissues.
What is ring down artifact?
“Ring-down” is an ultrasound artifact that appears as a solid streak or a series of parallel bands radiating away from abdominal gas collections.
What does edge shadowing mean?
(d) Diagram shows edge shadowing (defocusing) at the edge of a cystic structure with a different speed of sound than that of the surrounding medium. Refraction is greatest at the edges, resulting in shadowing due to the decreased beam intensity to deeper tissues.
What causes comet tail artifact?
Comet-tail artefact arises from reverberation of the US beam within a small cyst or gas bubble. The multiple echoes generated register as a trail on the image.
Which artifact may be caused by the spectral gain being too high?
When the gain setting is too high, the velocity envelope is degraded and a significant amount of noise artifact is produced in the background of the spectral graph; this can result in the appearance of spectral broadening.
What is dirty shadowing in ultrasound?
Clean and dirty shadowing are common phenomena in ultrasound (US) imaging. Clean shadowing is thought to be produced by sound-absorbing materials (ie, stones), and dirty shadowing is thought to be produced by sound-reflecting materials (ie, abdominal gas), but these properties are not consistent.
What are comet tails on lung ultrasound?
Comet-tails or “B-lines” are defined as hyperechoic reflections which originate only from and travel roughly perpendicular to the pleural line of the lung. They have a narrow base and form a ray spreading away from the transducer towards the bottom of the screen and synchronously move with lung respiration.
Do comet tails point away from the sun?
Comet tails come in two types. Comet tails will always point away from the sun because of the radiation pressure of sunlight. The force from sunlight on the small dust particles pushing them away from the sun is greater than the force of gravity acting in the direction toward the sun.
What causes aliasing in ultrasound?
Most sonographers encounter aliasing with pulse spectral Doppler or color Doppler. Pulsed ultrasound doesn’t have a particular upper limit for displaying the Doppler shift. It’s commonly known as the Nyquist limit. High-velocity blood circulation causes Doppler shifts beyond the Nyquist limit resulting in aliasing.
