Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is normal in size . The mediastinal contours are normal . As compared to prior chest radiograph and in conjunction with torso CT from ___ , new opacification in the left lower lung has characteristics more typical of atelectasis rather than pneumonia . The right lung is clear . There are no definite pleural effusions . No pneumothorax is seen . Healed left - sided rib fractures are noted .
    OUTPUT:
    
New moderate left lower lobe atelectasis , rather than pneumonia .