Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The large left pleural effusion has improved significantly compared to yesterday 's radiograph . However , it now appears to be loculated . The left pigtail catheter is unchanged in position . The right lung is essentially clear without evidence of pneumonia , pleural effusion or pneumothorax . Heart size is within the upper limits of normal . No acute osseous abnormalities .
    OUTPUT:
    
Significant interval improvement in large left pleural effusion , which now has a loculated appearance .