Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiomediastinal silhouette is normal in size . The thoracic aorta is tortuous and calcified . The lungs appear clear , except for mild right basilar atelectasis . No evidence of pneumothorax . A retrocardiac opacity is thought to be due to a large hiatal hernia . No prior scans available for comparison . Incidental note made of hardware overlying the midline mandible , as well as to surgical clips in the soft tissues in the region of the right neck .
    OUTPUT:
    
1 . No pneumothorax or large pleural effusions . 2 . A retrocardiac opacity likely due to a large hiatal hernia .