Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac , mediastinal and hilar contours are normal . A patchy opacity is noted in the retrocardiac region , new in the interval , which may reflect an area of infection . The right lung is clear . No pleural effusion or pneumothorax is identified . No acute osseous abnormalities seen .
    OUTPUT:
    
New patchy retrocardiac opacity concerning for infection .