# Low Volume of gray matter in CSD

**URL:** <https://community.mrtrix.org/t/low-volume-of-gray-matter-in-csd/7075>\
**Category:** Uncategorized\
**Created:** [November 2, 2023, 3:03pm UTC](https://community.mrtrix.org/t/low-volume-of-gray-matter-in-csd/7075 "2023-11-02T15:03:38Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![armin](https://community.mrtrix.org/letter_avatar_proxy/v4/letter/a/b9e5f3/32.png) [@armin](https://community.mrtrix.org/u/armin)\
**Post date:** [November 2, 2023, 3:03pm UTC](https://community.mrtrix.org/t/low-volume-of-gray-matter-in-csd/7075/1 "2023-11-02T15:03:38Z")

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Hi everyone.  
I applied csd msmt (dhollander) on a DTI image that contains two b values (0 and 800), and I’ve got the wmfod, gmfod, and csffod, but when I combined them, I figured out the gray matter is missed and I got an image that just contained red and blue color. Did I miss any thing?

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**Author:** ![ebrahim](https://community.mrtrix.org/user_avatar/community.mrtrix.org/ebrahim/32/4400_2.png) [@ebrahim](https://community.mrtrix.org/u/ebrahim)\
**Post date:** [November 2, 2023, 4:36pm UTC](https://community.mrtrix.org/t/low-volume-of-gray-matter-in-csd/7075/2 "2023-11-02T16:36:04Z")

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I think MSMT CSD requires at least 2 nonzero b-values

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**Author:** ![armin](https://community.mrtrix.org/letter_avatar_proxy/v4/letter/a/b9e5f3/32.png) [@armin](https://community.mrtrix.org/u/armin)\
**Post date:** [November 2, 2023, 6:46pm UTC](https://community.mrtrix.org/t/low-volume-of-gray-matter-in-csd/7075/3 "2023-11-02T18:46:35Z")

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So how can I do the msmt of images that were acquired with one nonzero b-value?

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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:** [November 2, 2023, 7:40pm UTC](https://community.mrtrix.org/t/low-volume-of-gray-matter-in-csd/7075/4 "2023-11-02T19:40:05Z")

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Hi @armin,

I think you’ll find the answers to these questions on [this previous post](https://community.mrtrix.org/t/mtnormalise-nan-values-as-balance-factors/4552/16) (amongst others on the topic, try searching for e.g. “msmt single shell”).

All the best,  
Donald