Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well expanded . A subtle opacity is seen in the right lung base which likely reflects atelectasis but can not exclude aspiration or pneumonia in the right clinical setting There is no pleural effusion or pneumothorax . There is severe cardiomegaly , slightly increased from prior exam .
    OUTPUT:
    
Subtle opacity in the right lung base which likely reflects atelectasis , but can not exclude aspiration or pneumonia right clinical setting .