Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Endotracheal tube tip terminates approximately 3 .1 cm from the carina . Heart size is normal . Mediastinal and hilar contours are unremarkable . Pulmonary vasculature is normal . Patchy opacity within the left lung base likely reflects an area of atelectasis , somewhat improved compared to the prior study . Tubular radiopaque density projecting over the heart size may be external to the patient . There is no large pleural effusion or pneumothorax . No acute osseous abnormalities demonstrated .
    OUTPUT:
    
1 . Standard positioning of the endotracheal tube 2 . Left basilar atelectasis , slightly improved in the interval .