Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are within normal limits . The pulmonary vasculature is not engorged . Linear opacities in the lung bases are compatible with areas of subsegmental atelectasis , slightly progressed in the interval . No focal consolidation , pleural effusion or pneumothorax is detected . No subdiaphragmatic free air is present .
    OUTPUT:
    
Bibasilar subsegmental atelectasis . No subdiaphragmatic free air