Dear Steve,
Thanks for your response, and my apology for not being very clear.
Basically, I found results in thalamus and am wondering whether I should
interpret the results as though skeltonized tracts are associated with
"Oxford thalamic connectivity atlas." When I compared default
skletonized atlas provided by FSL with the connectivity atlas,
skletonized tracts do not appear to resemble the connectivity atlas.
Question: Can I interpret TBSS results in thalamus and relate that with
connectivity atlas?
Thanks in advance,
Hedok
Steve Smith wrote:
> Hi,
>
> You are correct in saying that the search direction ('perpendicular'
> to the local skeleton) is determined purely by the local gradient (and
> second derivative) of the FA, and not taking into account tensor
> eigenvalues. There are many other sources of information that can
> potentially aid the registration, including the eigenvectors, but
> we've concentrated on what seems to matter the most.
>
> I wasn't sure what your actual question was?
>
> Cheers.
>
>
> On 24 Jul 2009, at 19:52, Hedok Lee wrote:
>
>> Dear FSLers,
>>
>>
>> I have a general question about projecting skeltonized FA onto a
>> template.
>>
>> From what I understand projection of the skeltonized FA is performed by
>> displacing skeltonized voxels to match a template skleton. This step
>> is done
>> by using a position of voxel and its FA, but it does not take into
>> account
>> for the direction of principal eigen vector in the voxel. In other word,
>> when principal eigenvector is weighted with FA map, we can color-code a
>> voxel with FA and its orientation (Red, Green, and Blue), so the
>> projection
>> should be done by matching not only FA but with its orientation as well
>> (being homologous may be the right term ?).
>>
>> I think this also applies to skeltonizing step too.
>>
>> Perhaps, I’m missing something here. Let me know if anybody has any
>> opinion
>> on this.
>>
>> Thanks,
>>
>> Hedok
>>
>
>
> ---------------------------------------------------------------------------
>
> Stephen M. Smith, Professor of Biomedical Engineering
> Associate Director, Oxford University FMRIB Centre
>
> 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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