Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . The pulmonary vascularity is normal . Linear opacities within the lung bases likely reflect subsegmental atelectasis . Mild elevation of the right hemidiaphragm is noted . The right costophrenic angle is not completely included in the field of view , though there is no large pleural effusion or pneumothorax identified . No acute osseous abnormalities are detected .
    OUTPUT:
    
Mild subsegmental atelectasis in the lung bases .