Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is at the upper limits of normal . The mediastinal contours demonstrate calcified atherosclerotic disease of the aortic knob . Lung volumes are somewhat low , with bibasilar atelectasis and scarring of the left base . There is no large pleural effusion or pneumothorax . There is no appreciable pulmonary edema . An old healed left posterior rib fracture is noted in the mid thorax .
    OUTPUT:
    
Left basal scarring and atelectasis .