Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are within normal limits . The pulmonary vasculature is not engorged . Patchy opacity in the left lung base likely reflects atelectasis . No focal consolidation , pleural effusion or pneumothorax is present . Mild degenerative changes are noted in the thoracic spine . Clips project over the epigastric region .
    OUTPUT:
    
Patchy left lower lobe opacity , likely atelectasis .