Lung comet tail image. ‘B lines’ also known as comet-tail images are a marker of pulmonary edema. In the presence of extravascular lung water the reflection of the ultrasound beam on the sub-pleural interlobular septa thickened by edema creates comet-tail reverberation artifacts. The ultrasound appearance is of a vertical, discrete, hyperechogenic image that arises from the pleural line and extends to the bottom of the screen moving synchronously with the respiration (white arrows)