Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is top - normal in size . No pneumonia . No pulmonary edema . No pleural effusion . No pneumothorax . Narrowing of the upper trachea can be seen with an enlarged thyroid .
    OUTPUT:
    
1 . No acute intrathoracic process . 2 . Narrowing of the upper trachea , which may be due to an enlarged thyroid .