Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is moderately low lung volume bilaterally with no areas of focal consolidation suspicious for infection . A retrocardiac opacity is again observed , consistent with atelectasis and essentially unchanged from prior study . There are no masses , lesions , pleural effusion or pneumothorax . The aorta is tortuous but not dilated ; otherwise the cardiomediastinal silhouette is within normal limits . The pleural surfaces are unremarkable . There are stable mild multilevel degenerative changes seen in the thoracic spine .
    OUTPUT:
    
No evidence of infection or malignancy .