Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral chest radiograph demonstrates a linear opacity at the left lung base , present on prior examination now more conspicuous . While this may reflect atelectasis , superimposed aspiration can not be excluded . Cardiomediastinal and hilar contours are unremarkable . There is no pleural effusion . Osseous structures are without acute abnormality .
    OUTPUT:
    
Linear opacity at the left lung base present on prior examination now more conspicuous and may reflect atelectasis although superimposed aspiration can not be excluded .