FINDINGS:
The lungs are well inflated and clear.  Marked prominence of the aortic knob
 is concerning for underlying aneurysm versus dissection.  Heart is normal in
 size.  There is no pneumothorax or pleural effusion.  Bony structures appear
 intact.

IMPRESSION:
Prominence of the aortic knob raises potential concern for aneurysm or
 dissection.  CTA of the chest is recommended for further evaluation.
 
 RECOMMENDATION(S):  CTA chest.