Lobar

Segmental

Subsegmental

 

Radiopaedia

“Air bronchogram refers to the phenomenon of air-filled bronchi (dark) being made visible by the opacification of surrounding alveoli (grey/white). It is almost always caused by a pathologic airspace/alveolar process, in which something other than air fills the alveoli. Air bronchograms will not be visible if the bronchi themselves are opacified (e.g. by fluid) and thus indicate patent proximal airways.

Air bronchograms can be seen with several processes:

• pulmonary consolidation
• pulmonary edema: especially with alveolar edema ³
• non-obstructive atelectasis
• severe interstitial lung disease
• neoplasms: bronchioloalveolar carcinoma; pulmonary lymphoma
• pulmonary infarct
• pulmonary hemorrhage
• normal expiration

Air bronchograms that persist for weeks despite appropriate antimicrobial therapy should raise the suspicion of a neoplastic process. CT may be planned in such cases.”

 

Links and References

Fleischner Society

air bronchogram

Radiographs and CT scans.—An air bronchogram is a pattern of air-filled (low-attenuation) bronchi on a background of opaque (high-attenuation) airless lung (^,Fig 2). The sign implies (a) patency of proximal airways and (b) evacuation of alveolar air by means of absorption (atelectasis) or replacement (eg, pneumonia) or a combination of these processes. In rare cases, the displacement of air is the result of marked interstitial expansion (eg, lymphoma) (^,8).