Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval placement of right - sided pigtail catheter projecting over the right lower lung . Right - sided pneumothorax has significantly decreased in size . There is no mediastinal shift . No acute osseous abnormalities .
    OUTPUT:
    
Interval decrease in size of right - sided pneumothorax status post pigtail catheter placement .