Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Cardiac silhouette is upper limits of normal in size . Aorta is tortuous . Lung volumes have improved compared to the prior study , and previously present area of opacity in the left lower lobe has markedly improved with only minimal residual atelectasis remaining . Small left pleural effusion has also slightly decreased in size . Right hemidiaphragm remains minimally elevated .
    OUTPUT:
    
Rapidly clearing left lower lobe opacity , which may have represented atelectasis or aspiration , with adjacent improving small left pleural effusion .