Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: In comparison to the CT chest obtained ___ , there appears to be increased narrowing of the trachea and widening of the right paratracheal stripe . On CT , this appeared to be due to a large brachiocephalic trunk . Lungs are fully expanded and clear without consolidations or effusions . Heart size is normal . Aortic knob and thoracic descending aorta are heavily calcified . Cardiomediastinal and hilar silhouettes are otherwise normal . Pleural surfaces are normal .
    OUTPUT:
    
Narrowing of the trachea may be caused by a a large brachiocephalic trunk or alternatively lymphadenopathy or hematoma in the appropriate clinical settings .