Hi - fdt_paths and seeds_to_targets do not contain the same information, that is why your results are not the same.
In your case you want to use method1.
Have a look at the probtrackx doc where these files are described.
Cheers
Saad
On 11 Apr 2012, at 02:38, Zhong Suyu wrote:
> Dear FSL experts:
>
> I am freshman of FSL.
>
> I am trying to do whole brain probabilistic tractography and to calculate connection probabilities between a set of N regions.
> First, I set one of the ROIs(i=1....N) as the seed mask , set all the rest ROIs as the stop mask(--stop), and set a list of targets that include all ROIs. And do protrackx. As a result,I got NXN seed(m)_to_<targets>(n) (m,n=1....N) files and N fdt_path files (each fdt_path contain the connectivity distribution from one of the N seed mask ROIs to the rest ROIs ).
> And then I determine the NxN connections in two ways: the fist way is sum the value of each voxel within each seed(m)_to_<targets>(n) file as the mth row and the nth column element of the connection. The second way is to use the fdt_path and fslstats command.
>
> I want to know if the results from the two methods are same. In my experiment, I got the different results.
> I find the number of samples got from seed_to_<target> is less than the one from fdt_path. Is it right? If yes, why the numbers are not the same?
>
>
> Thank you in advance!
>
> Suyu
>
--
Saad Jbabdi
University of Oxford, FMRIB Centre
JR Hospital, Headington, OX3 9DU, UK
(+44)1865-222466 (fax 717)
www.fmrib.ox.ac.uk/~saad
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