Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top normal with mild unfolding of the thoracic aorta . Hilar contours are unremarkable . There is minimal widening of the superior mediastinum , unchanged from prior study and likely represents vascular structures or mediastinal fat . Lungs are clear . There is no pleural effusion or pneumothorax . The osseous structures are grossly unremarkable .
    OUTPUT:
    
No acute intrathoracic process .