Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs and pleural spaces are clear without evidence of pneumothorax or pleural effusions . The heart is normal in size . Re-demonstration of retrocardiac opacity is seen and likely reflects hiatal hernia . Surgical clips project under the diaphragm . Osseous structures are unchanged .
    OUTPUT:
    
No acute intrathoracic process .