Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate persistent retrocardiac and left mid lung opacification which may represent atelectasis , though pneumonia is still a consideration . There is interval improved aeration of the right lung base likely due to improved inspiration . Cardiomediastinal and hilar contours are unremarkable . No pleural effusion or pneumothorax .
    OUTPUT:
    
Persistent retrocardiac and left mid lung opacification could be consistent with mild pneumonia in the correct clinical setting .