Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is subtle opacification of the left lower lung . No pleural effusion or pneumothorax is detected . Heart and mediastinal contours are within normal limits .
    OUTPUT:
    
Subtle opacification of the left lower lung , which could represent infection . Comparison to prior exams would be helpful if available . Findings were discussed with Dr . ___ by ___ by telephone at 7 :00 p .m . on ___ , at the time of initial review of the study .