Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac , mediastinal and hilar contours are normal . Pulmonary vasculature is normal . Lung volumes are low with streaky opacity in the retrocardiac region most likely reflective of atelectasis . No pleural effusion or pneumothorax is present . No acute osseous abnormalities demonstrated .
    OUTPUT:
    
Streaky retrocardiac opacity , likely atelectasis in the setting of low lung volumes .