Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette size is normal . The aorta is tortuous . Mediastinal and hilar contours are unremarkable . The pulmonary vasculature is not engorged . Linear opacities in the left lung base are compatible with subsegmental atelectasis . No focal consolidation , pleural effusion , or pneumothorax is present . Moderate multilevel degenerative changes are noted in the thoracic spine .
    OUTPUT:
    
Left basilar subsegmental atelectasis . No radiographic evidence for pneumonia .