Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiograph demonstrate a subtle opacity in the left lower lobe posteriorly overlying the lower thoracic spine on the lateral view with associated slight obscuration of the posterior left hemidiaphragm . Streaky opacity at the left lung base thought likely atelectatic in etiology . Heart size is normal . Patient is status post median sternotomy . Wires appear intact . Surgical clips project over the left mediastinal border . No evidence of pulmonary edema , pleural effusion , or pneumothorax .
    OUTPUT:
    
Possible early / focal pneumonia in the left lower lobe .