Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette size remains mild to moderately enlarged . The mediastinal and hilar contours are unchanged . Pulmonary vasculature is not engorged . Linear opacities within both lung bases are compatible with areas of subsegmental atelectasis . No focal consolidation , pleural effusion or pneumothorax is visualized . Moderate multilevel degenerative changes are seen in the thoracic spine .
    OUTPUT:
    
Subsegmental atelectasis in the lung bases . No pneumonia or pulmonary edema .