Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Left base opacity is seen which is felt to more likely represent atelectasis rather than pneumonia . Aspiration is not entirely excluded . There are low lung volumes . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are unremarkable . Gaseous distention of bowel is partially imaged . No evidence of free air is seen beneath the diaphragm .
    OUTPUT:
    
Low lung volumes . Left base opacity most likely represents atelectasis