Chest ultrasound syndromes: typical sonographic findings and relevant differential diagnoses

Chest ultrasound syndromeSonographic featuresDifferential diagnosis
 PneumothoraxAbsent lung sliding
Absent B-lines
Lung point (specific for pneumothorax)
Pneumothorax, emphysema, pleural adhesions
 Pleural effusionEcho-free space
Quad sign (fluid-colour and sinusoid signs more specific for effusion)
Pleural effusion, pleural thickening, parenchymal fluid collection
 ConsolidationTissue-like pattern (iso- or hypo-echoic)
Echogenic air-bronchograms
Pneumonia, atelectasis, neoplasm, pulmonary infarct
 Interstitial syndromeB-linesDiffuse: cardiogenic pulmonary oedema, non-cardiogenic pulmonary oedema, interstitial lung disease
Focal: pneumonia, focal fibrosis, pulmonary contusion, pulmonary infarction, lymphangitis
 Chest wall applicationsInterrupted parietal pleura and restricted pleural movement in the context of subpleural massMalignant chest wall invasion
 Diaphragm applicationsImpaired thickening
Reduced excursion
Diaphragmatic paresis, extrinsic limitation of diaphragm