Pneumomediastinum in a ventilated patient

(A) Chest radiograph in a patient with asthma shows radiolucent streaks in the mediastinum tracking into the lower neck and a radiolucent line outlining the left margin of the mediastinum (arrows).
(B) Coronal reformation of chest computed tomography performed 1 hour later better demonstrates the linear lucencies (arrows) in the mediastinum diagnostic of pneumomediastinum.