Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Subtle streaky left base retrocardiac opacity and is most likely due to atelectasis . No definite focal consolidation is seen . There is no pleural effusion or pneumothorax . The cardiac silhouette is top - normal . Mediastinal contours are unremarkable .
    OUTPUT:
    
Subtle streaky left base retrocardiac opacity is most likely due to atelectasis .