Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP view of the chest . The right right - sided port ends in the upper SVC . A new left lower lobe retrocardiac opacity may represent aspiration or pneumonia or atelectasis . No pleural effusion or pneumothorax . The lungs are otherwise clear . Cardiomediastinal and hilar contours are normal .
    OUTPUT:
    
Vague retrocardiac opacity most likely atelectasis , however aspiration or pneumonia can not be ruled out .