[Mristudio-users] questions about Fiber tracking

[wyzyf at mail.ustc.edu.cn]

    Hello professor,

       Thank you very much for your helpful instructions.

       So, can I say like this? I can do population-averaged seed based fiber tracking without image registration but only FA(vector) or tensor value calculated by DTI studio adding the 3D masking files that define the tract locations?

       Sorry to trouble you so much ,and best wishes!

                                        Ying Wang 




-----Original E-mail-----
From: "Susumu Mori" <smoriw at gmail.com>
Sent Time: 2013-8-17 1:33:24
To: "DTI Studio, ROI Editor, DiffeoMap Questions/Support" <mristudio-users at mristudio.org>
Cc:
Subject: Re: [Mristudio-users] questions about Fiber tracking


Hi Ying, 


Here is my view of "registration".


> Imaging is all about what is where.
> When you quantify images, you have to make sure that you are measuring the same structures or locations across subjects. This act of identifying the same thing is "registration".
> For example, you can manually define the hippocampus across subjects. By doing so, you identify a group of voxels that belong to the hippo and you "register" the hippo locations across subjects. You defined corresponding voxels across subjects. In this sense, manual ROI delineation is one of the registration methods.
> Because the manual delineation is time consuming, people don't want to do it. Then what we do is to align all images and assume all voxels are registered automatically. This means, if I pick up an arbitrary location (like a single voxel), I can immediately locate the corresponding location (voxel) in each subject by using the same x, y, z coordinates.
> Tractography can also be considered as a registration tool because, for example, we can identify a group of voxels that belong to the corticospinal tract across subjects. Therefore, there is nothing wrong with defining the cst in each subject without image-alignment.
> However, there could be several reasons why you may want to do image alignment (thus voxel-by-voxel registration) first and then additional registration by tractography. First, tractography requires manually (or automatically) defined  ROIs for seed and destination. This could be done more reproducibly if all images are aligned. Second, after tracts are defined, you can easily create population-averaged probabilistic maps by simply adding the 3D masking files that define the tract locations. On the other hand, if you are just interested in voxel count (size of the tract) and FA values, image alignment may not be necessary.


Susumu



On Fri, Aug 16, 2013 at 2:25 AM, <wyzyf at mail.ustc.edu.cn> wrote:



  Hello professor:

    As I understood, fiber tracking analysis with DTI studio should be a group analysis and image registration is
  necessary. Am I right?

    I have finished the image registration with DiffeoMap through linear and nonlinear(b0+FA) registration but I don`t
  know how to achieve group analysis and the registrated FA doesn`t match the origin vector.

    Thank you very much~!

                                                    Ying Wang
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