CT scan of right lung atelectasis

Computed tomography (CT) scan of the chest with mediastinal window setting shows the rotational shift of the mediastinum to the right with complete opacification and loss of volume of the right lung. A small posteromedial pleural effusion is present (arrow) and is less opaque than the adjacent collapsed lung. The effusion is probably due to the decreased relative pleural pressure in the right hemithorax following the collapse of the right lung.