Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is persistent left basilar opacity likely due to scarring given persistence dating back to ___ . The lungs are otherwise clear . There is trace left pleural effusion improved since most recent prior . The cardiomediastinal silhouette is within normal limits . Tortuous descending thoracic aorta is noted . Hypertrophic changes are seen in the spine . No acute osseous abnormalities identified .
    OUTPUT:
    
Persistent left lung base linear opacity suggestive of scarring given persistence . Trace left effusion .