Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a triangular retrocardiac opacity , which likely represent left lower lobe atelectasis . The right lung is clear . There is no evidence for pulmonary edema , pneumothorax or pneumonia . The heart is top - normal in size . The mediastinum and hilar contours are unremarkable . SVC vascular stent seen . Tracheostomy tube appears unchanged in position . A large bore catheter is seen in the expected location of the IVC , unchanged from prior . Percutaneous gastrostomy tube appears unchanged .
    OUTPUT:
    
New left lower lobe atelectasis .