Slide 1: Question 1. Your patient presents with severe dyspnea, fever and cough. What is the name of the arrowed finding? What does it mean?

Slide 2: Answer 1. Normally, bronchi are hard to see. Thin-walled black air-filled bronchi blend in with black air-filled alveoli. But if alveoli are airless due to alveolar collapse (atelectasis) or the air is replaced by soft tissue density (consolidation) like pus, then black air-filled bronchi stand out on a background of abnormal white lung, creating air bronchograms (pointed to by the arrows). Graphic showing a normal lung with no air bronchograms. Air showing a atelectatic or consolidated lung with air bronchograms.

Slide 3: Coronal CT lung and soft tissue windows confirm that the lung is soft tissue density, but the bronchi remain air filled. CT scan showing lung window and soft tissue window. Question 2. What do air bronchograms tell you?

Slide 4: Answer 2. That it’s the lung that is abnormal. The lung is abnormal due to alveolar collapse or alveoli filled with blood, pus, etc. In this case, the history of fever and cough led to the correct diagnosis of pneumonia. But be careful. Even with “air-space” disease, you may not see air bronchograms.

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