Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Minimal cortical step - off within the lower sternum is suspicious for a minimally displaced sternal fracture . Heart size is mildly enlarged . The aorta is tortuous . Mediastinal and hilar contours are unremarkable . Pulmonary vasculature is normal . Linear and patchy opacities are seen in both lung bases , likely atelectasis . No focal consolidation , pleural effusion or pneumothorax is demonstrated .
    OUTPUT:
    
1 . Minimal cortical step - off involving the lower sternum is suspicious for a minimally displaced sternal fracture . 2 . Bibasilar atelectasis .