Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is top - normal is calcified . Hilar contours are unremarkable . There is a small linear opacity in the left lower lobe , not seen previously . There is no pulmonary edema or pleural effusion . There are mild endplate degenerative changes in the spine .
    OUTPUT:
    
Small linear opacity in the left lower lobe is compatible with atelectasis , but pneumonia can not be excluded .