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Forum TrackVis Usage The meaning of "Track Count"

The meaning of "Track Count"
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2:19 pm
July 14, 2010


gaolion

Member

posts 6
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Dear Ruopeng,

First let me thank you for this fantastic software, I've been with it for quite a time and now prepared to write up something based on the result of TrackVIS.

Here I get a question. It's good that the track count can be shown for each ROI, e.g., the track count of genu ROI is 300 in the young while only 200 in the elderly, which means the elderly have less tracks.

Obviously, the number 300 or 200 is not the real neuro-fibers, as my voxel is 2*2*3 and the ROI is 2-mm ball,  I don't think that trackVIS or any other tractographic technical can ever really figure out the fibers  histologically. So what's the meaning of the track count shown by trackVIS? Does it represent the fiber density or volume density, or anything parallel to real fibers? how does the number come out?

Sorry that this may be general question for all tractography. While I wonder whether you may  help to explain a bit more if reviewers would become suspicious or curious on these part of result from TrackVIS.

Thanks very much in advance!

Gao

10:26 am
July 15, 2010


Ruopeng

Admin

posts 114
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Hi Gao,

When Diffusion Toolkit does the fiber tracking, it starts a track from the center of every voxel, thus creates a big family of tracks. The track count in TrackVis is the number of the tracks from that family that touch the ROI (or meet whatever criterion you set for track filtering).

So to compare track numbers between scans, one should make sure they have the same geometry information, e.g., voxel size, etc.

Cheers,

Ruopeng
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