Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral radiographs of the chest demonstrate well - expanded lungs . There is increased opacification of the retrocardiac space which is concerning for pneumonia or aspiration . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Increased retrocardiac opacity is could be due to pneumonia or aspiration .