Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low , likely due to elevation of the diaphragm . There are patchy retrocardiac opacities which may reflect atelectasis versus pneumonia . Otherwise , the lungs appear clear . No pneumothorax or pleural effusion seen .
    OUTPUT:
    
Patchy retrocardiac opacities localizing to the left lower lobe on the lateral projection may reflect atelectasis or pneumonia .