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Dear Freesurfer experts,
We appreciate any advice or guidance from your community of professionals
and experts in the field about the issue below.

Thank you for your kindness.

Dear Freesurfer experts,
In order to normalize white matter intensity of T1 images and correct for
bias field. We do the following steps:
mri_convert T1.nii.gz T1.mgz
mri_nu_correct.mni --i T1.mgz --o T1_N3.mgz --n 2
mri_normalize -g 1 T1_N3.mgzT1_norm.mgz
mri_convert T1_norm.mgz T1_norm.nii.gz

We would like to apply bias field correction on FLAIR images then
normalize white matter intensity.
We tried N4biasfieldcorrection from ANTS but it didn't work as expected.
Reviewing documents about N4biasfieldcorrection we realize that the
algorithm has been developed to correct bias field correction in T1 not
clear if it works on FLAIR images.

Are the steps above valid for normalizing FLAIR images or can it only be
applied on T1 images? I would like to send a "recon-all.log" file that
includes the processing steps of FLAIR. Is there any link I can use to
upload the file. It gets rejected every time I send it due to size
limitations.

We appreciate any feedback about the proper way to correct FLAIR images for
bias fields and normalize white matter intensity in FLAIR images.

Thank you
JamesB

On Wed, Sep 21, 2022 at 10:18 AM James Brown <jb1979...@gmail.com> wrote:

> Dear Freesurfer experts,
> In order to normalize white matter intensity of T1 images and correct for
> bias field. We do the following steps:
> mri_convert T1.nii.gz T1.mgz
> mri_nu_correct.mni --i T1.mgz --o T1_N3.mgz --n 2
> mri_normalize -g 1 T1_N3.mgzT1_norm.mgz
> mri_convert T1_norm.mgz T1_norm.nii.gz
>
> We would like to apply bias field correction on FLAIR images then
> normalize white matter intensity.
> We tried N4biasfieldcorrection from ANTS but it didn't work as expected.
> Reviewing documents about N4biasfieldcorrection we realize that the
> algorithm has been developed to correct bias field correction in T1 not
> clear if it works on FLAIR images.
>
> Are the steps above valid for normalizing FLAIR images or can it only be
> applied on T1 images? I would like to send a "recon-all.log" file that
> includes the processing steps of FLAIR. Is there any link I can use to
> upload the file. It gets rejected every time I send it due to size
> limitations.
>
> We appreciate any feedback about the proper way to correct FLAIR images
> for bias fields and normalize white matter intensity in FLAIR images.
>
> Thank you
> JamesB
>
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