# Problem of "masks" in Mrtrix

**URL:** https://community.mrtrix.org/t/problem-of-masks-in-mrtrix/1172
**Category:** Uncategorized
**Created:** [September 14, 2017, 4:32pm UTC](https://community.mrtrix.org/t/problem-of-masks-in-mrtrix/1172 "2017-09-14T16:32:48Z")
**Posts on this page:** 1
**Showing post:** 3

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### Author: ![SuperClear](https://community.mrtrix.org/user_avatar/community.mrtrix.org/superclear/32/2222_2.png) [@SuperClear](https://community.mrtrix.org/u/SuperClear)
#### Post date: [September 16, 2017, 4:39pm UTC](https://community.mrtrix.org/t/problem-of-masks-in-mrtrix/1172/3 "2017-09-16T16:39:38Z")

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Thank you for your patient reply.  
Fig 8 is a really cool result！ I love it very much.🤩

Do you mean my problem may not only list on the mask, but also FOD?

My bval file is as follows:

 ![Hardi150_bval](https://community.mrtrix.org/uploads/default/original/1X/abd04179a67463123366d2152a81c9b6263f6da0.png)

In my case, it seems a single-shell DWI, [As shown here, ss3t\_csd is not available yet.](http://community.mrtrix.org/t/wm-odf-and-response-function-with-dhollander-option---single-shell-versus-multi-shell/572/4)do you mean that I can use `"msmt_csd"` instead of `"csd"` when I use `dwi2fod` to fiber orientation distribution estimation? [Just like the document,](https://mrtrix.readthedocs.io/en/latest/fixel_based_analysis/st_fibre_density_cross-section.html) so that I can strike out the gray matter.

By the way, Figure 9 is really fantastic. However, Global Tractography seems to run on a cohort of images. I just test one single DWI data, does Global Tractography fit me? I want to try it then. 😯

Fig 9: (Global Tractography)

 ![global-tractography](https://community.mrtrix.org/uploads/default/original/1X/7db746b46da7ebcdcfd75882c1a69547c113a39f.jpg)

Many Thanks,  
Chaoqing

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