Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are slightly low . There is a left retrocardiac opacity . A dome - shaped opacity at the right base could reflect pleural fluid . The mid and upper lung fields are clear . The heart is moderately enlarged . There is no frank pulmonary edema . There is no pneumothorax .
    OUTPUT:
    
1 . Left retrocardiac opacity could reflect aspiration or pneumonia . 2 . Suspected unilateral right pleural effusion , in the setting of worsening moderate cardiomegaly , raises concern for pulmonary embolism .