Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low accentuating the cardiac silhouette and pulmonary vasculature . Within this context , heart size is normal . Prominent widening of the upper mediastinum , significantly incrased compared to prior . Hilar contours are normal . Lungs are clear . Pleural surfaces are clear without effusion or pneumothorax .
    OUTPUT:
    
Prominent interval widening of the upper mediastinum may be secondary to low lung volumes and technique . Recommend repeat PA and lateral study and if this finding persists , this must be evaluated with CT .