Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle retrocardiac basilar opacity seen on the lateral view is not well substantiated on the frontal view and could be due to aspiration or subtle infectious process . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Subtle basilar retrocardiac opacity seen on the lateral view , not well substantiated on the frontal view , could be due to aspiration or subtle infectious pneumonia .