Air bronchogram

Air Bronchogram is a radiologic sign used in the field of medicine, specifically in radiology and pulmonology. It refers to the phenomenon where air-filled bronchi (tubes leading into the lungs) are made visible by the opacification of surrounding alveoli (air sacs in the lungs). It is a common finding in many lung diseases, including pneumonia, lung cancer, and acute respiratory distress syndrome (ARDS).

Definition

An air bronchogram is defined as a pattern in lung imaging where air-filled bronchi can be seen against a background of opacified lung tissue. This is typically seen in a chest x-ray or a computed tomography (CT) scan of the chest. The air-filled bronchi appear as dark (radiolucent) structures against the denser, white (radiopaque) lung tissue.

Pathophysiology

The pathophysiology of the air bronchogram sign is related to the filling of the alveoli surrounding the bronchi with fluid, cells, or other material that increases the density of the lung tissue. This can occur in various lung diseases, such as pneumonia, where the alveoli are filled with inflammatory cells and fluid, or lung cancer, where the alveoli are filled with cancer cells. The air in the bronchi stands out against this background, creating the air bronchogram sign.

Clinical Significance

The presence of an air bronchogram on a chest x-ray or CT scan can help in the diagnosis of several lung conditions. It is most commonly associated with pneumonia, but can also be seen in other conditions such as lung cancer, ARDS, and pulmonary edema. The pattern of the air bronchogram, along with other imaging findings and clinical information, can help to differentiate between these conditions.

See Also

• Radiology
• Pulmonology
• Pneumonia
• Lung cancer
• Acute respiratory distress syndrome
• Pulmonary edema