A common misunderstanding in lung ultrasound: the comet tail artefact.

The comet tail artefact is probably one of the most commonly and imprecisely used to describe vertical artefacts found in lung ultrasound. Two distinct artefacts are commonly observed: the lung comets and the B-lines. Both artefacts differ with regard to generation mechanism and clinical significance. This review explores the current understanding and use of these two artefacts in lung ultrasound and suggests how to avoid the pitfalls related to confusing comet tail artefacts with other vertical artefacts.