6 directions is generally too few for a robust probabilistic solution.
w/r to 1, i would tend to average the coregistered / eddy-current-corrected runs and perform further computations on the average. (simply because it would be less time consuming.)
w/r to 2, yes - flirt can register to the b0-image (corrratio puts up well with the liquor being bright on b0 but dark on the other images), i.e you can simply put it first to use it as the default reference volume.
Von: Russ Poldrack [mailto:[log in to unmask]]
Gesendet: Di 07.12.2004 19:49
An: [log in to unmask]
Betreff: [FSL] dealing with multiple DTI runs
hi - we generally collect 5-6 runs of DTI data using a 6-direction
sequence. I've just started playing around with FDT and I have a
couple of questions:
1 - Would you suggest putting all of the data from each run into
bedpost, or would you average the runs together (after
coregistering/eddy current correction) and then feed the average into
2 - I had previously used flirt to coregister across runs and to fix
eddy current distortions, but I now see that you have a script that
does this. One question: Is the eddy_correct program able to deal with
the tw-weighted (b=0) image as the target, or should it only be used
with b>0 images?
Russell A. Poldrack, Ph.D.
Assistant Professor of Psychology, UCLA
Franz Hall, Box 951563
Los Angeles, CA 90095-1563
email: [log in to unmask]