# Cant create a proper FOD?

**URL:** https://community.mrtrix.org/t/cant-create-a-proper-fod/7757
**Category:** Uncategorized
**Created:** [June 26, 2024, 5:22pm UTC](https://community.mrtrix.org/t/cant-create-a-proper-fod/7757 "2024-06-26T17:22:54Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![jdtournier](https://community.mrtrix.org/user_avatar/community.mrtrix.org/jdtournier/32/2594_2.png) [@jdtournier](https://community.mrtrix.org/u/jdtournier)
#### Post date: [July 4, 2024, 3:13am UTC](https://community.mrtrix.org/t/cant-create-a-proper-fod/7757/2 "2024-07-04T03:13:30Z")

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Hi @egemen4552,

Sorry if this comes a bit late – we’ve been busy preparing for and running the [MRtrix workshop](https://community.mrtrix.org/t/7311).

I wonder if your issue is similar to the one discussed in this post:

> [@Mtnormalise nan values as balance factors](https://community.mrtrix.org/t/mtnormalise-nan-values-as-balance-factors/4552/16):
>
> Yes, it looks like you have single-shell data (b = 0 & 1,000 s/mm²), which can’t directly support a 3-tissue decomposition – but your dwi2fod call does request 3 tissue types. This is why the GM segment is coming out all wrong (though I would have expected it to come out closer to straight zeros…). There are thankfully other options for dealing with single-shell data: use the [original single-shell CSD method](https://mrtrix.readthedocs.io/en/latest/constrained_spherical_deconvolution/constrained_spherical_deconvolution.html) (i.e. dwif2fod csd). This will only rely on the b=1,000 s/mm² data. use the new MSMT-…

Have a look and see if this is relevant, and let us know if that doesn’t fix the issue.

All the best,  
Donald

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