Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . There are linear opacities at the left lung base , which represent atelectasis . Otherwise , the lungs are clear . No pleural effusion or pneumothorax is seen . Posterior spinal hardware appears to be in similar configuration in comparison to the prior chest radiograph , although dextroscoliosis of the thoracic spine persists .
    OUTPUT:
    
No evidence of pneumonia .