Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Tracheostomy tube in - situ . Low lung volumes . New linear opacity present in the left lung base which may represent atelectasis . No pneumothorax . Right - sided PICC line in situ with the tip in the proximal right atrium . The increase in vascular markings are thought to be secondary to the low lung volumes . Presumed small effusions .
    OUTPUT:
    
New linear opacity present in the left lung base most likely represents atelectasis .