Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . The pulmonary vascular is normal . Linear bibasilar airspace opacities are compatible subsegmental atelectasis . There is no pleural effusion or pneumothorax . No acute osseous abnormalities seen . Asymmetry of the rib cage is unchanged , compatible with patient 's prior history of multiple chest surgeries .
    OUTPUT:
    
Bibasilar subsegmental atelectasis .