Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are notable for mild left lower lobe linear plate like opacity only seen on frontal projection , consistent with atelectasis . The right lung is clear . No pleural effusion or pneumothorax . Heart size , mediastinal contour , and hila are unremarkable . Mild degenerative changes of the thoracic spine are noted .
    OUTPUT:
    
Left lower lobe opacity is most consistent with atelectasis . No pneumonia .