Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal and hilar contours are normal . Atherosclerotic calcifications are demonstrated at the aortic knob . Pulmonary vasculature is normal . Linear opacities in the left lung base likely reflect areas of subsegmental atelectasis or scarring . No focal consolidation , pleural effusion or pneumothorax is present . Bilateral shoulder arthroplasties are partially imaged . There are moderate multilevel degenerative changes seen in the thoracic spine .
    OUTPUT:
    
No evidence of pulmonary edema . Left basilar subsegmental atelectasis or scarring .