Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral images of the chest demonstrate improved pulmonary vascular congestion since previous imaging . The lateral view demonstrates a spine sign which suggests a retrocardiac opacity which is worrisome for pneumonia . There are mild bibasilar atelectatic changes . It is not clear on this exam if there are pleural effusions . There is no pneumothorax visualized . The cardiomediastinal silhouette is unremarkable . Visualized osseous structures are unremarkable .
    OUTPUT:
    
Improved pulmonary vascular congestion . New retrocardiac opacity worrisome for pneumonia .