Comet Tail Artefact CTA and RingDown Artefact RDA

The term comet tail artefact [CTA ] in LUS has caused confusion simply because it is used to describe any vertical artefact, in particular B-lines, which is an ringdown artefact [RDA]. CTA and RDA are generated by distinct mechanisms; while reverberation due to acoustic impedance difference is the mechanism of generating CTA, RDA are caused by resonant vibration due to bubble tetrahedral complexes or their equivalents.

Their appearance in LUS will depend on the state of the lung to provide the right acoustic environment for their generation, in both healthy and diseased patients. Using pneumothorax and interstitial syndrome as examples, we illustrated that the lung comets (CTAs) and B-lines (RDA) have distinct roles in disease diagnosis and the potential pitfalls if they are simply lumped together and called CTAs.