Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Faint peribronchial opacification likely in the left lung base is of uncertain significance and may reflect atelectasis though very mild pneumonia or aspiration is not fully excluded . The remainder of the lungs are clear . The heart is normal in size . Normal cardiomediastinal silhouette .
    OUTPUT:
    
Faint left lung opacity could reflect atelectasis , aspiration or pneumonia .