Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Right - sided PICC terminates in the mid SVC and is unchanged . An endotracheal tube dens 2 .2 cm above the carina . Lung volumes are markedly low . Given that , cardiomediastinal and hilar contours are unchanged . There is significant atelectasis of the left base . There is no evidence of pneumonia . There are small bilateral pleural effusions . No evidence of pneumothorax
    OUTPUT:
    
Severe left basal atelectasis and small bilateral pleural effusions , improved since ___ . There is no evidence of pneumonia .