Slide 1: Question 1: What is the best description of the findings on this portable chest x-ray?

Slide 2: Answer 1: Complete opacification of the left hemithorax! Question 2: What are the two most likely etiologies for the radiographic findings?

Slide 3: Answer 2: Pleural effusion and atelectasis! Question 3: What does the purple arrow on the coronal CT image show?

Slide 4: Answer 3: Occlusion of the left main bronchus. In this patient, the occlusion is from an endobronchial mass, which is difficult to see in the lung windows. Question 4: What structure normally projects over the dashed teal line and why is it displaced to the left?

Slide 5: Answer 4: Right atrium, displaced because of left-sided volume loss (atelectasis). Normally, the right atrium projects into the right middle lobe, but here it is pulled into the left chest by the collapse of the left lung due to left bronchus occlusion. // Differential diagnosis of Complete Opacificiation of Hemithorax on CXR: 1. Normal CXR – Both lungs filled with air, mediastinum (and heart) slightly on left. 2. Atelectasis – volume loss leads to mediastinum (and heart) pulled towards the opacification. 3. Pleural effusion – volume gain leads to mediastinum (and heart) pushed away from the opacification.