Confluent B-lines. Multiple confluent B-lines (asterisks) and occupying ≥ 50% of the field of view define the “rocket launch” sign or “glass rockets.” This is associated with more overt interstitial syndrome. Additional file 1: Clip S1: Anterior parasagittal scan of the thorax. The parietal and visceral pleura appear as a hyperechoic line. Pleural sheaths are seen sliding with respiration