Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are well inflated . Retrocardiac opacity is present . No pleural effusion or pneumothorax . Left heart border is partially obscured . Visualized cardiomediastinal silhouette is unremarkable . Hila are normal . Visualized osseous structures are unremarkable . No displaced rib fracture .
    OUTPUT:
    
1 . Retrocardiac opacity is worrisome for pneumonia or aspiration . 2 . Although no fracture or other bone abnormality is seen , conventional chest radiographs are not appropriate for detection or characterization of chest cage lesions . Any focal findings should be clearly marked and imaged with either bone detail views or CT scanning .