Dear Saad,
I think that I found an answer for my question.
Thank you so much for your detailed and patient reply.
Best regards,
Kim
On Tue, 3 Mar 2015 16:58:51 +0000, Saad Jbabdi <[log in to unmask]> wrote:
>Hi - there is nothing for you to estimate, probtrackx does that for you.
>
>Imagine that N is the total number of sample streamlines that probtrackx runs (seed voxels times #streamlines per voxel).
>Then P of those streamlines do not make it to the waypoint mask, for example.
>
>In that case, the waytotal value that probtrack outputs is equal to: waytotal = N-P
>
>Is this clearer?
>
>Saad
>
>On 3 Mar 2015, at 13:58, Kim TRAN <[log in to unmask]<mailto:[log in to unmask]>> wrote:
>
>Dear Saad,
>
>Thank you very much for the speedly reply. But could you please tell me how to calculate the excluded streamlines? I didn't find it in the file fdt.tcl. I realy need to understand the nature of these number to best use. Thanks alots.
>
>Best regards,
>
>Kim
>
>
>On Tue, 3 Mar 2015 11:15:46 +0000, Saad Jbabdi <[log in to unmask]<mailto:[log in to unmask]>> wrote:
>
>The excluded streamlines are not the same between subjects, for many reasons, for example: the streamlines are probabilistic, different subjects have different anatomies, different subjects have different bedpost output, etc.
>
>
>On 3 Mar 2015, at 10:57, Kim TRAN <[log in to unmask]<mailto:[log in to unmask]><mailto:[log in to unmask]>> wrote:
>
>Dear Saad,
>
>Thanks a lot for your reply. However, I haven't understood how can the waytotal be different for different subjects? To my knowledge, it just depends on the parameters built up (i.e. waytotal = total number sent - excluded streamlines, https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=FSL;808dbdf3.0903).
>
>Thus, I want to compare the mean intensity within a ROI, so I set the same parameters for each subjects. But now, the waytotal numbers are all differents, can I continue my method of comparison or I should normalize these results with waytotal number?
>
>Thanks so much for your help,
>
>Kim
>
>------------------------------------------------------------------
>Saad Jbabdi, PhD
>MRC Career Development Fellow &
>University Research Lecturer
>
>FMRIB Centre, University of Oxford,
>John Radcliffe Hospital, Oxford, OX3 9DU, UK.
>tel (+44)1865-222466 (fax 717)
>www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi<http://www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi><http://www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi>
>
>
>
>
>
>------------------------------------------------------------------
>Saad Jbabdi, PhD
>MRC Career Development Fellow &
>University Research Lecturer
>
>FMRIB Centre, University of Oxford,
>John Radcliffe Hospital, Oxford, OX3 9DU, UK.
>tel (+44)1865-222466 (fax 717)
>www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi<http://www.ndcn.ox.ac.uk/team/researchers/saad-jbabdi>
>
>
>
>
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