Q)Explain the radiology of pneumothorax.

A: The diagnosis of even small quantity of air in pleural cavity (1ml) can be made with good quality radiographs. When seen on erect radiographs, pleural air rises to the lung apex & depending on amount of air, ipsilateral lung becomes transradiant.

Rarely, expiratory/decubitus films may help to confirm the diagnosis. In supine position, pleural air rises & collects anteriorly, particularly medially & basally.

When pleural space is partly obliterated, a pneumothorax may be loculated. It must be differentiated from other loculated transradiancy like cysts, bullae, pneumatoceles.

CT may help in doubtful case.

When fluid accompanies a pneumothorax, air fluid level is more eye-catching.

(L) Pyopneumothorax