Ultrasound pattern of normal lung. The pleural line (white arrow) is a roughly horizontal hyperechoic line 0.5 cm below the upper and lower ribs identified by acoustic shadow (R). A single vertical artifact arising from the pleural line and spreading up to the edge of the screen (comet-tails, indicated by asterisk) can be seen in dependant regions in normally aerated lungs.
Bouhemad et al. Critical Care 2007 11:205 doi:10.1186/cc5668