title: The Luftsichel: an old sign in upper lobe collapse.
abstract: The Luftsichel is a paramediastinal translucency due to interposition of the apex of the lower lobe between the mediastinum and the shrunken upper lobe. It occurs more commonly on the left than the right. It is so common on the left that it should be regarded as the typical appearance. It is to be distinguished from mediastinal hernia.
mesh_terms: D001984:Bronchial Neoplasms / Q000150:complications; D003937:Diagnosis, Differential; D006547:Hernia / Q000000981:diagnostic imaging; D006801:Humans; D008477:Mediastinal Diseases / Q000000981:diagnostic imaging; D001261:Pulmonary Atelectasis / Q000000981:diagnostic imaging* / Q000209:etiology; D011859:Radiography