Hi Loic - The command that computes the motion measures is dmri_motion, and it can take either the eddy_correct or eddy format as input. The former format contains affine registration matrices with respect to the reference frame (which usually is the first b=0). The latter format contains the shift/rotation/etc. parameters of the registration rather than the matrix itself. You can run dmri_motion without arguments to see details.

Best,

a.y

From: freesurfer-bounces@nmr.mgh.harvard.edu <freesurfer-bounces@nmr.mgh.harvard.edu> on behalf of Daumail, Loic Jean <LDAUMAIL@mgh.harvard.edu>
Sent: Tuesday, June 12, 2018 5:33:17 PM
To: freesurfer@nmr.mgh.harvard.edu
Subject: [Freesurfer] dwi.ecclog file

Hello,

I have several questions regarding the dwi.ecclog file data from Tracula, using the FreeSurfer version V6.0.0.

1) Does Tracula still use eddy_correct from FSL, or was it updated with the new eddy function from FSL?

2) Are the values for each slice of dwi.ecclog relative to the first slice or to the previous slice, or to another template? is it the same for both rotation and translation values?

3) What is the coordinate system for the rotation values? Is there a way to determine the total rotation from these 9 values?

Thanks,

Sincerely,

Loic Daumail