Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiographs were provided . Lung volumes are slightly low . Opacity at the left base may be atelectasis ; however infection can not be excluded . There is no pleural effusion or pneumothorax . The cardiomediastinal silhouette is unchanged and notable for a tortuous aorta . The bones are intact .
    OUTPUT:
    
Left basilar opacity which may represent atelectasis or infection .