Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . Streaky linear left basilar opacities extend to the hilum and likely represent atelectasis . The right lung demonstrates linear right basilar atelectasis and is otherwise grossly clear . There is no right pleural effusion , pneumothorax , or frank pulmonary edema . The cardiomediastinal silhouette appears unchanged from the prior several examinations .
    OUTPUT:
    
Waxing and waning left lower lobe airspace opacity which demonstrates a morphological appearance suggestive of atelectasis , although superimposed infection or aspiration is difficult to exclude .