Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP view of the chest was reviewed . Cardiomediastinal and hilar contours are stable . Lung volumes are low with stable bibasilar opacities . Pulmonary vasculature is within normal limits . Probable post traumatic changes of the left shoulder are again seen .
    OUTPUT:
    
Bibasilar opacities which are most likely atelectasis given low lung volumes . Pneumonia or aspiration are not excluded .