Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable frontal image of the chest . There are low lung volumes . An area of opacity is seen at the left lung base , which could reflect atelectasis but can not exclude aspiration or pneumonia in the right clinical context . The lungs are otherwise clear . No large pleural effusion or pneumothorax is seen . The cardiomediastinal silhouette is mildly enlarged but similar to prior exam . The aorta is again noted to be tortuous and dilated , unchanged from prior exam . An area of calcification is seen overlying the right neck , unchanged from prior exams .
    OUTPUT:
    
Opacity at the left lung base , which could reflect atelectasis but can not exclude aspiration or pneumonia in the right clinical context .