The tool to use is: track_transform

It should be distributed with the DTK / TrackVis tools.

-Lilla

On Wed, 9 Nov 2011, Douglas N Greve wrote:

> Hi Paolo, I don't think we have have any tools to apply a matrix to a
> trk file. Or maybe I'm wrong?
> doug
>
> paolo wrote:
>> Bruce, Doug, Thomas, thank you so much, things are getting slowly
>> clearer now
>>
>> I can try to explain better what i want to do, so that perhaps
>> it will be easier for you too to tell what is the best way
>> to approach this problem
>>
>> essentially we have a number of subjects, with already extracted
>> white matter fiber tracts (in .trk format)
>> The idea was to transform these  fibers back to freesurfer space (is
>> it the talairach space? in any case, is this what happens by using the
>> talairach.xfm matrix?), and then compare them in this space, as, i would
>> guess, there is still some sort of deviation from the standard fiber
>> pathway.
>>
>> Is this unreasonable?
>>
>> also, just for visualization purposes, i was thinking of rendering
>> these fibers in their context, but the average brain is, as you point
>> out, a bit too blurry.
>> Would it make sense here to bring something like MNI152 into the
>> freesurfer space, and use this one (and its segmentation) instead of the
>> fsaverage as an illustrative atlas in freesurfer space?
>>
>> Paolo
>>
>>
>>
>> On Mon, 7 Nov 2011 11:41:46 -0500 (EST)
>> Bruce Fischl <[email protected]> wrote:
>>
>>
>>> Hi Paolo,
>>>
>>> Are you showing individual subject data in the MNI space, or group
>>> average data? In general showing template brains and average data is
>>> not a good idea. It misrepresents the spatial localization accuracy
>>> of the data. You should try to use averages of the anatomy for groups
>>> of tracts of average fmri data or other group stats/data.
>>>
>>> cheers
>>> Bruce
>>>
>>> On Mon, 7 Nov 2011, Paolo wrote:
>>>
>>>
>>>> I think it is well possible.
>>>> And in principle i just wanted to use it for presentation, but the
>>>> fsaverage doesnt really look like a "template" brain, rather like
>>>> an average
>>>>
>>>> that's why i was wondering whether there is a more realistic
>>>> template available in freesurfer space, or how i can create one
>>>> (the idea was to recon-all the MNI152, which to me resembles much
>>>> more to a brain)
>>>>
>>>> would it be the correct approach, or do you have other suggestions?
>>>> by the way is it normal that recon-all on mni152 takes just ages to
>>>> complete? (>12 hours on an athlon64, dont know exactly how long, i
>>>> always stopped it before it finished)
>>>>
>>>> Paolo
>>>>
>>>>
>>>> On 07-Nov-11 16:03, Thomas Yeo wrote:
>>>>
>>>>> I am probably wrong, but doesn't the volumetric part of fsaverage
>>>>> correspond to MNI305 space rather than MNI152 space?
>>>>>
>>>>> --Thomas
>>>>>
>>>>> On Mon, Nov 7, 2011 at 9:00 AM, Bruce
>>>>> Fischl<[email protected]>  wrote:
>>>>>
>>>>>> Hi Paolo,
>>>>>>
>>>>>> I think fsaverage has this in the aseg.mgz.
>>>>>>
>>>>>> cheers
>>>>>> Bruce
>>>>>> On Mon, 7 Nov 2011, Paolo wrote:
>>>>>>
>>>>>>
>>>>>>> In the meanwhile i did some research, and it looks like
>>>>>>> freesurfer does not use MNI152 as default template, am i right?
>>>>>>> it seems that the default template is the fsaverage subject,
>>>>>>> which in fact does not look like very realistic.
>>>>>>>
>>>>>>>
>>>>>>> Is there any way to get a realistic brain&  segmentation that is
>>>>>>> "idealized" enough, and still in talairach space (freesurfer
>>>>>>> space)?
>>>>>>>
>>>>>>> maybe the MNI152 after recon-all and mri_transform to apply back
>>>>>>> the transformation?
>>>>>>>
>>>>>>> i am sorry if these questions look unreasonable, i am new of
>>>>>>> freesurfer, and still have problem orienting myself in the
>>>>>>> documentation :)
>>>>>>>
>>>>>>> best,
>>>>>>> Paolo
>>>>>>>
>>>>>>> On 05-Nov-11 00:57, Paolo wrote:
>>>>>>>
>>>>>>>> Hello
>>>>>>>>
>>>>>>>> I am a new user of freesurfer.
>>>>>>>> I was wondering whether the brain regions for the MNI152
>>>>>>>> dataset are available anywhere (i mean the template brain
>>>>>>>> regions for the default MNI152 template).
>>>>>>>>
>>>>>>>>
>>>>>>>> I have also another question: i have the dti fiber tracts
>>>>>>>> extracted and computed and already in .trk format.
>>>>>>>> I was wondering: to bring them back into the template MNI152
>>>>>>>> space, is it sufficient to apply the talairach.xfm
>>>>>>>> transformation matrix to the vertex data, or do i also need to
>>>>>>>> use the m3z files (which look like a nonlinear deformation
>>>>>>>> field)?
>>>>>>>>
>>>>>>>> thanks in advance!
>>>>>>>> Paolo
>>>>>>>>
>>
>>
>>
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>
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