Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . Heart size is top normal . Mediastinal and hilar contours are within normal limits . Pulmonary vasculature is normal . No focal consolidation , pleural effusion or pneumothorax is present . Retrocardiac patchy opacity is most likely reflective of atelectasis . There are no acute osseous abnormalities .
    OUTPUT:
    
Low lung volumes with retrocardiac patchy opacity most likely reflective of atelectasis .