Right lower lobe atelectasis

Atelectasis of the right lower lobe characterized by a triangular opacity in the right lower hemithorax (arrow). It has an oblique sharp border towards the rest of the aerated lung that is formed by the major fissure. The overall volume in the right hemithorax is reduced when compared with the left lung. The right hilum is displaced caudally and is partially obscured by the collapsed lobe. The right cardiac border and the right hemidiaphragm are outlined by the hyperexpanded right middle lobe.