Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single frontal view of the chest demonstrates tracheostomy in place . There is a dense retrocardiac opacity and bilateral lung bases which could represent atelectasis . Patchy opacities in the left base likely represent atelectasis although infection should be considered in the appropriate clinical setting . The cardiomediastinal silhouette is within normal limits allowing for low lung volumes . Upper lungs are clear . Thoracic aorta is prominent and unfolded .
    OUTPUT:
    
Patchy left basilar opacity and retrocardiac opacities likely represent atelectasis although supervening infection must be considered in the appropriate clinical setting .