Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Relatively low lung volumes are noted with streaky left basilar including retrocardiac opacity which is likely atelectasis . Elsewhere , lungs are clear . The cardiomediastinal silhouette is within normal limits . No acute osseous abnormalities .
    OUTPUT:
    
Left basilar opacity which is likely atelectasis in setting of low lung volumes . Infection can not be excluded in the proper clinical setting . If desired , PA and lateral could be attempted for further clarification .