A PA chest radiograph shows low left lung volume, haziness of the left lung with obliteration of the left heart border, a Luftsichel sign (arrowheads).
A lateral chest radiograph shows an anteriorly displaced left major fissure (arrows). The collapsed left upper lobe is up against the anterior chest wall.
- Seen on PA chest radiograph of patients with left upper lobe collapse
- Paraaortic crescent of air with sharp margin extending anywhere from left apex to left superior pulmonary vein
- Luft = air; sichel = sickle [German]
- Caused by expansion of superior segment of left lower lobe due to left upper lobe collapse.
- In adults, it is an important clue to diagnose collapse that may be due to an obstructing endobronchial neoplasm.
- On PA view: Low left lung volume (elevated diaphragm), haziness of the left lung with obliteration of left heart border, elevated left hilum, near-horizontal course of the left main bronchus, Luftsichel sign
- On lateral view: Anteriorly displaced major fissure that parallels the anterior chest wall