Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Semi upright view of the chest provided . Bilateral perihilar densities are increased compared to prior . Pulmonary edema is mild . Bilateral pleural effusions are small . There is no pneumothorax . Left lung curvilinear scarring is similar to prior . Heart size is enlarged , as on prior . . Aortic arch calcifications are seen . Sternal wires are intact . 2 prosthetic valves are seen .
    OUTPUT:
    
Bilateral perihilar densities could represent atelectasis or pneumonia .