Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unchanged . Pulmonary vasculature is not engorged . Elevation of the right hemidiaphragm is chronic . Linear opacities in the lung bases likely reflect areas of subsegmental atelectasis or scarring . No focal consolidation , pleural effusion or pneumothorax is identified . Moderate to severe multilevel degenerative changes are again seen in the thoracic spine .
    OUTPUT:
    
Bibasilar subsegmental atelectasis or scarring .