Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low as they had been on prior , however there is a new left basilar opacity . Elsewhere , lungs are clear . Cardiomediastinal silhouette is within normal limits . No acute osseous abnormalities .
    OUTPUT:
    
While atelectasis may explain left basilar opacity in the setting of low lung volumes , similarly decreased lung volumes were present on prior . Therefore , this new opacity may represent superimposed infection .