Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single semi-upright AP portable view of the chest was obtained . Patchy left base retrocardiac opacity could be due to atelectasis or infection . Slight blunting of the left costophrenic angle is felt to most likely be due to overlying soft tissue . No large pleural effusion or pneumothorax . Cardiac silhouette is not enlarged . The aorta is tortuous .
    OUTPUT:
    
Patchy left base retrocardiac opacity may represent atelectasis , although consolidation due to infection is not excluded .