Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A frontal view of the chest was obtained . The patient is rotated . Slightly increased retrocardiac opacity is likely atelectasis although infection can not be excluded in the appropriate clinical setting . There is linear atelectasis in the left mid lung . There is no pleural effusion or pneumothorax . Cardiac and mediastinal silhouettes and hilar contours are stable allowing for patient position . No upper abdominal or osseous abnormality is identified .
    OUTPUT:
    
Retrocardiac opacity is likely atelectasis although infection can not be excluded in the appropriate clinical setting . If further imaging evaluation is needed , a lateral view could be obtained .