Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle right middle lobe airspace opacity is noted , which have increased from the prior examination . Lung volumes are low . There is no large pleural effusion , pneumothorax , or overt pulmonary edema . The cardiomediastinal silhouette is within normal limits .
    OUTPUT:
    
Increased opacity at the right medial lung base , which may represent atelectasis versus a developing pneumonia