[Mrtrix-discussion] eddy correction and ideal number of streamlines for TDI

[Todd Jolly]

Hi all,
I have been looking into using streamtrack SD_PROB for whole brain tracking to create TDI. My dMRI sequence was acquired on a 3T Siemens Verio, voxel size 2.2mm isotropic, using diffusion gradient b=3000 with 64 directions. I was wondering if anyone would have any advice or suggestions in regard to the following:

1. Should perform eddy_current corrections on my dMRI images as the mrtrix wiki does not show a step for eddy current correction? I didn't want to use FSL just in case there were errors with the bvec gradient scheme when using it in mrtrix.

2. I also get the following error:
disp_profile: unexpected number of SH coefficients - assuming response function

My input is as follows
erode subjectIDmask.mif -npass 3 - | mrmult subjectIDfa.mif - - | threshold - -abs 0.7 subjectIDsf.mif
estimate_response subjectIDdwi.mif subjectIDsf.mif -lmax 8 subjectIDresponse.txt
disp_profile -response subjectIDresponse.txt

I think I saw a post where Donald said that this has been fixed in the latest version so should I upgrade my version/ redo all analyses?

3. What is the optimum number of streamlines needed to achieve good quality TDI, I have seen some people use 4 million but others have used 2 million?

Thanks,
Todd
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.nitrc.org/pipermail/mrtrix-discussion/attachments/20121212/2af71c63/attachment.html