Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a left retrocardiac opacity , more pronounced compared to ___ . This may represent atelectasis , although infection should be considered in the appropriate clinical setting . There is also bronchial wall thickening , left greater than right . Mild pulmonary vascular congestion , without evidence of overt pulmonary edema . Heart size is mildly enlarged .
    OUTPUT:
    
1 . Left retrocardiac opacity , may represent atelectasis or infection . 2 . Mild pulmonary vascular congestion .