Left lower lobe collapse
LLL collapse. This example shows the classic ‘sail sign’ of left lower lobe collapse. The left lower lobe collapses like a fan, becoming triangular in shape. Its lateral border is visible as a line (white arrows) behind the heart shadow. The medial aspect of the left hemidiaphragm disappears because it has dense collapsed lung adjacent to it rather than aerated alveoli. This patient also has a tracheostomy (yellow arrows) and a right internal jugular venous line.