Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Chest PA and lateral radiograph demonstrates unremarkable hilar , and cardiac contours . There is a small irregularity in the contour of the aortic arch . Bilateral low lung volumes cause vascular crowding . No focal opacification evident . No pleural effusion or pneumothorax identified . No displaced fractures present .
    OUTPUT:
    
Abnormal contour of aortic arch may represent clinically insignificant anatomic variant or represent a significant finding , depending on the mechanism of injury . ___ conveyed these findings to Dr ___ at ___ :___ on ___ .