Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Mild to moderate enlargement of the cardiac silhouette is unchanged . Mediastinal and hilar contours are similar . No pulmonary edema , pleural effusion or pneumothorax is present . Patchy retrocardiac opacity likely reflects atelectasis . No acute osseous abnormalities demonstrated .
    OUTPUT:
    
Minimal retrocardiac atelectasis . Otherwise , no acute cardiopulmonary abnormality .