Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There better lung volumes in the study . There is a retrocardiac opacity with apparent air bronchograms , likely representing a pneumonia in the left lower lobe . The right lung is grossly clear . No pleural effusion or pneumothorax . The mediastinal contours are normal . Cardiac and hilar contours are normal .
    OUTPUT:
    
Likely left lower lobe pneumonia . Recommend follow up in ___ weeks to ensure resolution .