Hi - the FAST segmentation includes bias field correction within it,
so you don't need to worry about this.
The intensity range scaling is unrelated to bias field. The
segmentation in FAST is not sensitive to the absolute scaling, so you
can probably get away with just working out the scaling for the
greatest-range image and using that for all inputs, as long as the
smallest intensity images are not a _tiny_ fraction of the greatest.
Cheers.
On 7 Sep 2007, at 18:24, Jamie Hanson wrote:
> Hello all-
>
> I am a newbie to the list, so I apologize if this question has been
> recently answered (I searched the archives, but didn't see any answers
> right off the bat).
>
> But I was wondering if you are using the basic analytic pathway
> specified in the "FSL-VBM" approach, whether you should bias correct
> first (before creating a study specific template, etc)?
>
> Related to this, I have been running fslstats and finding the need to
> use greatly different scaling parameters. For some T1s, the ranges are
> from 0 to 6000, while other are 0 13000 (and every value in between).
> There is definitely no consistent scaling factor I could apply. Does
> that mean bias correction is needed first?
>
> Thoughts? Suggestions?
>
> Best,
> jamie.
>
>
>
>
> --
> Jamie L. Hanson
> Waisman Laboratory for Brain Imaging & Behavior | Child Emotion
> Research Lab
> University of Wisconsin - Madison
> 1500 Highland Avenue
> Madison, WI 53706
> Phone: (608) 262-5148
> ***Please note my new email: [log in to unmask]***
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Stephen M. Smith, Professor of Biomedical Engineering
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FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
+44 (0) 1865 222726 (fax 222717)
[log in to unmask] http://www.fmrib.ox.ac.uk/~steve
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