Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are new opacities at both lung bases , greater on the left than right , although mid and low upper lungs remain clear . There is no pleural effusion or pneumothorax . The cardiac , mediastinal and hilar contours appear stable .
    OUTPUT:
    
Basilar opacities of substantial extent ; although possibly explained by atelectasis or pneumonia , findings could be seen with aspiration pneumonitis in the appropriate setting .