Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable chest radiograph demonstrates unremarkable cardiomediastinal and hilar contours . Compared to prior chest radiograph there are slightly lower lung volumes with a slighlty more conspicuous retrocardiac opacification is seen with faint bronchograms identified , new compared to recent CT and may represent developing atelectasis or aspiration in setting of known T12 burst fracture . The small pneumothorax identified on CT is not identified on radiography , which is less sensitive . No pleural effusion present . Endotracheal tube and enteric tube well positioned .
    OUTPUT:
    
Known small pneumothorax identified on CT is not evident on radiograph . Lower lung volumes with slightly increased retrocardiac opacification , atelectasis versus aspiration in setting of trauma .