Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Spinal fixation hardware extending from the thoracic spine to the lower level of the film is incompletely visualized but grossly similar to prior without migration or fracture . The heart is normal size . Retrocardiac atelectasis is similar to prior and may represent aspiration in the correct clinical setting . No pneumothorax or substantial pleural effusion .
    OUTPUT:
    
Retrocardiac opacity , similar to ___ , which may represent aspiration in the correct clinical setting .