Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . The heart size is borderline enlarged . Mediastinal and hilar contours are unremarkable . There is crowding of the bronchovascular structures . Minimal patchy opacity in the retrocardiac region could reflect atelectasis in the setting of low lung volumes . No pleural effusion or pneumothorax is present . There is no pulmonary vascular congestion . No acute osseous abnormalities are seen .
    OUTPUT:
    
Patchy retrocardiac opacity may reflect atelectasis in the setting of low lung volumes . Infection can not be completely excluded .