Hi Russ,
it may depend on the number of runs. Occasionally, you may see eddy currents becoming less compensated the more DWI runs you acquire without interruption. I guess I would favor to correct for eddy currents and motion and then average but it's probably not much of an effort to simple try both ways and compare the results.
Hope all is well,
best wishes-
Andreas
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Von: FSL - FMRIB's Software Library im Auftrag von Russ Poldrack
Gesendet: Mi 14.03.2007 21:43
An: [log in to unmask]
Betreff: [FSL] fitting dti data over multiple runs
hi - we have some DTI datasets where we have collected multiple runs of a 30-direction sequence (within the same imaging session, so there is relatively little displacement between the acquisitions). Is there any benefit to collapsing the data into a single file, aligning, and running dtifit on the entire dataset at once, as opposed to running dtifit separately on the individual runs and then averaging the FA maps?
cheers
russ
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Russell A. Poldrack, Ph.d.
Associate Professor
Wendell Jeffrey and Bernice Wenzel Term Chair in Behavioral Neuroscience
UCLA Department of Psychology
Franz Hall, Box 951563
Los Angeles, CA 90095-1563
phone: 310-794-1224
fax: 310-206-5895
email: [log in to unmask]
web: www.poldracklab.org
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