Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low , particular in the left lung were there is elevation of the left hemidiaphragm and a left basal opacity , likely reflecting atelectasis . Superimposed infection can not be excluded . Lungs are otherwise clear . Moderate unfolding of the thoracic aorta . Surgical clips consistent with a prior thyroidectomy . No pneumothorax or pleural effusion seen . Moderately severe degenerative changes in the thoracic spine .
    OUTPUT:
    
Left basal opacity likely reflects atelectasis , superimposed infection can not be excluded .