Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is mildly enlarged . The mediastinal and hilar contours appear unchanged . There is persistent retrocardiac opacity obscuring the medial left hemidiaphragm , although it appears less extensive than on the prior study , comparing the lateral views . The shape of the residual opacity is convex on the lateral view . Background prominence of interstitial markings is somewhat improved suggesting improvement in vascular congestion . Marked hyperinflation is similar . Bony demineralization and loss in vertebral body heights along the lower thoracic spine appear similar .
    OUTPUT:
    
Improving left lower lobe opacity with a substantial residual convex opacity , however . Differential considerations include round atelectasis or loculated pleural effusion . A mass is also not possible to exclude at this site , however . Depending on clinical circumstances , continued radiographic surveillance could be considered to show resolution or alternatively the opacity could be evaluated with chest CT , preferably with intravenous contrast if possible , when clinically appropriate .