Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph obtained . There is right basal linear density which is most compatible with atelectasis or scarring . There is mild retrocardiac opacity which may also represent atelectasis , though the possibility of an early pneumonia is impossible to exclude . Cardiomediastinal silhouette is stable . The mid - to - upper lungs appear relatively well aerated allowing for technique .
    OUTPUT:
    
Probable basilar atelectasis . No definite signs of pneumonia .