Hi Eddy,
I'm not sure I follow 100% of what you're saying...
The FMRIB58 was created by *linearly* placing in the MNI space all the 58 FA images using the MNI 152 T1w template. Then only the *mean FA* was iteratively used to non-linearly register all the 58 images.
I don't think you should use a GM template in the way you describe as there are distortions in the DW images that make some structures of your GM segmented image and the corresponding best FA target non comparable. This is why all the strategies in TBSS 2nd step (-T or -S) are using a registration from an FA image to another FA image (either the best FA target or the FMRIB58).
Hope this helps,
Gwenaëlle
--- En date de : Lun 27.4.09, Eddy D.L. <[log in to unmask]> a écrit :
> De: Eddy D.L. <[log in to unmask]>
> Objet: [FSL] Question about FMRIB58_FA standard-space model
> À: [log in to unmask]
> Date: Lundi 27 Avril 2009, 15h29
> Hi to all,
> I have a question about FMRIB58_FA standard-space model.
> Before building
> this model has been done a prealignment the gray matter?
> Because I want built a template DTI from more subjects, and
> for alignment of
> white matter I think to use the TBSS method, but for this
> purpose I need to
> know if FMRIB58_FA is built considerating the alignment of
> gray matter. If
> the model does not considers this, I might use VBM process
> to find the
> "best" target between my DTI study group, select
> the candidate that present
> a minimal change (basing on .msf files), subsequently I
> take correspondent
> FA image to warping in standard space of GM ICBM152(using
> the warp file
> computed in VBM process). Then I use this last image as the
> reference in
> tbss process.
> Is this conceptually correct?
>
> Thanks,
>
> Cheers
>
> Eddy
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