Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is moderately enlarged , unchanged . The aortic knob is calcified . The mediastinal and hilar contours are similar . There is no pulmonary edema . Streaky opacity in the retrocardiac region is demonstrated . No pleural effusion or pneumothorax is identified . There are no acute osseous abnormalities .
    OUTPUT:
    
Streaky retrocardiac opacity is most likely suggestive of atelectasis but infection can not be completely excluded in the correct clinical setting .