Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Unchanged mild cardiomegaly with mild central vascular congestion and pulmonary edema , slightly improved since the prior study . Linear left lower lobe atelectasis . A subtle , left retrocardiac airspace opacity may represent atelectasis versus pneumonia . No large pleural effusion or pneumothorax . Metallic embolization coils are noted overlying the right upper quadrant .
    OUTPUT:
    
Mild cardiomegaly and central vascular congestion . Left lower lobe and retrocardiac airspace opacities likely reflects atelectasis , although underlying infection is difficult to exclude .