Fill the holes(Closing) isn't working

I used local threshold in order to get artery.
It works well but there are some holes…
So I also used Smoothing after this process but it doesn’t work.
(it isn’t working, actually. but in this case, doesn;t work at all)


These are huge holes, not even holes but rather an insufficient segmentation. Fill holes works well on holes inside a closed surface segment. Increase the kernel size according to the size of the inner holes. If this gets too big, smoothing may be a very long process. So it’s really best to segment better.

Thank you for the fase reply!!! I found another way to improve this work.
3D brush with threshold works well.