CT Chest (preferred diagnostic test)
CXR
AP/PA - Ring around right pulmonary artery, air along left heart border, air in upper chest/neck soft tissue
Lateral - air along anterior heart border
Lateral neck - may see mediastinal air in neck
30% with spontaneous<unk>  will have normal CXR
AP/PA - Ring around right pulmonary artery, air along left heart border, air in upper chest/neck soft tissue
Lateral - air along anterior heart border
Lateral neck - may see mediastinal air in neck
30% with spontaneous<unk>  will have normal CXR
Pneumomediastinum
Acute coronary syndromes 
Hemothorax
STEMI
Chylothorax
Non-STEMI
Pneumopericardium
Unstable angina