# Clipping Tractography
**URL:** https://discourse.slicer.org/t/clipping-tractography/8129
**Category:** Support
**Created:** [August 21, 2019, 9:53pm UTC](https://discourse.slicer.org/t/clipping-tractography/8129 "2019-08-21T21:53:29Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@cindy](https://discourse.slicer.org/u/cindy)
#### Post date: [August 21, 2019, 9:53pm UTC](https://discourse.slicer.org/t/clipping-tractography/8129/1 "2019-08-21T21:53:30Z")
Hi all,
I’m looking for help to clip out a certain portion of a tract.
Thus far, I have created a mask at the root entry zone of the trigeminal nerve and used it for tractography seeding. I know have a fiber bundle, however I want to isolate only the portion of the nerve moving anteriorly from the brainstem. I know about the option to use a negative ROI in the tractography display module, but the entire length of all fibres within the ROI are removed - which isn’t what I’m trying to do. I am trying to eliminate any portions of my fiber bundle that is outside a region that I know my nerve should be.
Any help?
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### Author:  [@ljod](https://discourse.slicer.org/u/ljod)
#### Post date: [August 21, 2019, 10:30pm UTC](https://discourse.slicer.org/t/clipping-tractography/8129/2 "2019-08-21T22:30:54Z")
One option is to make a “brain mask” covering a large region where the nerve can go, but excluding the anterior region you are not interested in. If you use this as the brain mask in UKF tractography, it will stop any tracts leaving the mask.
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### Author:  [@cindy](https://discourse.slicer.org/u/cindy)
#### Post date: [August 21, 2019, 11:23pm UTC](https://discourse.slicer.org/t/clipping-tractography/8129/3 "2019-08-21T23:23:01Z")
Yea - that’s a good idea, but I already generated the tracts so I want a way to clip an existing one. Any ideas?
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### Author:  [@ljod](https://discourse.slicer.org/u/ljod)
#### Post date: [August 22, 2019, 12:33am UTC](https://discourse.slicer.org/t/clipping-tractography/8129/4 "2019-08-22T00:33:10Z")
This module is not yet integrated but does something close to what you want, if you have some computer science or Slicer module installation experience/interest:
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### Author:  [@neurohuo](https://discourse.slicer.org/u/neurohuo)
#### Post date: [October 17, 2021, 1:25am UTC](https://discourse.slicer.org/t/clipping-tractography/8129/5 "2021-10-17T01:25:13Z")
Thanks a lot, I think it is a very useful module.