Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Streaky left base retrocardiac opacity could be due to atelectasis or pneumonia . There is no pleural effusion or pneumothorax . The cardiac and mediastinal silhouettes are unremarkable . No evidence of free air is seen beneath the diaphragms .
    OUTPUT:
    
Streaky left base retrocardiac opacity could be due to atelectasis or pneumonia . No evidence of free air beneath the diaphragms .