Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . The heart is of normal size with normal cardiomediastinal contours . Lung volumes are low . Left lung base linear opacity is present , similar to ___ . No large pleural effusion or pneumothorax is present . No radiopaque foreign body . Multilevel thoracic spine degenerative changes .
    OUTPUT:
    
Left lung base linear opacity , most compatible with atelectasis or scarring , although aspiration is not excluded .