Hi, I am doing tractography and I was checking the forum and found this message. I am a beginner so I'm sorry if the question sounds silly but why is it necessary to do this if after running probtrackx one gets the waytotal that as far as I understand already contains the number of stream lines? What is the difference between what one gets doing this and the waytotal?

Thank you,


2014-05-22 6:08 GMT-07:00 Saad Jbabdi <[log in to unmask]>:
Hi
Can you try the same thing but after binarising the mask?   This should give you the same resuts with matlab and fslstats.

Saad

On 21 May 2014, at 18:39, Jiook Cha <[log in to unmask]> wrote:

Dear Saad and tractography experts,

I recently compared two different methods to count the number of streamlines on a fdt_paths image applying a target mask, which showed different results.

Firstly, I used [fslstats fdt_paths -M $mask] to get "mean of the values' and [fslstats fdt_paths -V $mask] to get the 'number of non-zero voxels".  I then multiply them.

Secondly, I load the fdt_path into matlab and just sum up all the values within the same mask.

These two measures, however, are not same. The first method show a 13% increase than the second summation on matlab.


Have you experienced a similar issue before? What method would you recommend?
Thanks for your help in advance.


Best,
Jiook

--
Saad Jbabdi
University of Oxford, FMRIB Centre

JR Hospital, Headington, OX3 9DU, UK
(+44)1865-222466  (fax 717)