Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA lateral images of the chest . The lung volumes are mildly decreased from prior exam . There is a retrocardiac opacity which is concerning for pneumonia or aspiration . There is a subtle medial right lung base opacity which may relate to vascular structures , but could also represent an additional site of consolidation . No large pleural effusion or pneumothorax is seen . The cardiomediastinal silhouette is unremarkable .
    OUTPUT:
    
1 . Retrocardiac opacity concerning for pneumonia or aspiration . 2 . Subtle medial right lung base opacity which may relate to vascular structures , but could also represent an additional site of consolidation .