Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Overlying trauma board limits assessment . Lung volumes are low which accentuate the heart size which is borderline enlarged . The mediastinal contours are within normal limits . There is crowding of the bronchovascular structures . Retrocardiac streaky opacity may reflect atelectasis . No pleural effusion or pneumothorax is grossly seen on this supine exam . There are no acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes with probable retrocardiac atelectasis .