Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is of normal size with normal cardiomediastinal contours . Lung volumes are low . No pleural effusion , or pneumothorax . Retrocardiac opacity is compatible with atelectasis . The left costophrenic angle is not well seen , likely due to overlying soft tissue . No radiopaque foreign body .
    OUTPUT:
    
Low lung volumes . Retrocardiac opacity is compatible with atelectasis .