Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is possible subtle left basilar retrocardiac opacity which may be due to atelectasis although underlying consolidation is not excluded . The right lung is clear . The lungs are clear without focal consolidation . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are stable .
    OUTPUT:
    
Possible subtle left basilar retrocardiac opacity seen on the frontal view may be due to atelectasis although underlying consolidation is not excluded . If symptoms continue , consider nonurgent chest CT .