Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Study is slightly limited due to lordotic positioning . The heart size is normal . Mediastinal and hilar contours are unremarkable . There is no pulmonary vascular congestion . Minimal streaky retrocardiac opacity likely reflects atelectasis . No focal consolidation , pleural effusion or pneumothorax is demonstrated . There are no acute osseous abnormalities .
    OUTPUT:
    
Probable retrocardiac atelectasis .