Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is borderline in size . The aortic arch is calcified . There is a convex contour to the upper right mediastinum with a smooth outer contour ; most often , this appearance is due to tortuosity of the great vessels and appears benign . Aside from streaky left basilar opacity suggesting atelectasis , the lungs appear clear . There is no pleural effusion on the right . Slight blunting of the left costophrenic angle may reflect a minimal effusion on the left side , however . Moderate degenerative changes affect the partly imaged upper lumbar spine .
    OUTPUT:
    
Possible trace pleural effusion and suspected minor atelectasis at the left lung base .