Atelectasis

cause: tumor (most SCC), TB, sarcoidosis, Post operative atelectasis. Large left atrium.
Types:
Resorption - Obstruction
Relaxation - Passive, Pleural effusion, pneumothroax
Adhesive - ARDS (decrease in surfatant production)
Cicatricial - Lung fibrosis
ex. right middle lobe syndrome
Discoid atelectasis: Emoblus, Penumonia, Inadequate inspiration Carcinoma
Segmental atelectasis
Sign
Double lesion sign - RUL and RML collapse
Shifting granuloma sign
Golden's S sign - RUL
Juxtaphrenic peak - UL
Luftsichel sign - LUL - Apical cap
Falt waist sign - LLL
Comet-tail sign - Rounded
Rounded atelectasis - Posterior lower lobe. often free pleural effusion with inflammation