Sign of Intraperitoneal Free Air

Rigler's sign
Triangle sign
Falciform ligament sign
Inverted V sign
Urachus sign
Hyperlucent liver sign
Hepatic age som
Doge cape sign
Anterior superior oal sign
Foot ball sign
Dolphin sign

Bowler Hat Sign

For differienation of polyp and diverticulm of colon.
Bowler hat pointing toward center of cup showed a polyp and pointing away from center of cup showed a diverticulum
When the bowler hat is nearly parallel to long axis of bowel, it is impossible to determine whether it is a polyp or a diverticulum

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