Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Relatively low lung volumes and elevation of the right hemidiaphragm are again noted . Streaky bibasilar opacities are likely secondary to atelectasis . Superiorly the lungs are clear . There is no effusion . The cardiomediastinal silhouette is within normal limits , prosthetic valve is again noted . Median sternotomy wires are again noted .
    OUTPUT:
    
Bibasilar atelectasis . No definite pneumonia .