Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: An endotracheal tube is present with the tip 6 cm from the carina . The lung volumes are low . The left costophrenic angle is not included in the field of view . A large dense retrocardiac opacity is most likely atelectasis . The lungs are otherwise clear . There is no pulmonary edema , pleural effusion , or pneumothorax . The cardiomediastinal silhouette is normal . The apparent widening of the mediastinum is due to prominent mediastinal fat .
    OUTPUT:
    
1 . Satisfactory positioning of the endotracheal tube , 6 cm from the carina . 2 . Dense retrocardiac opacity , which is most likely atelectasis .