Perhaps Saad can elaborate on that earlier (2010) post, and whether it is
still relevant.
That’s the first I’ve heard that simply concatenating the data would be
sub-optimal in terms of bedpostx performance (other than the run-time
issue).
cheers,
-MH
--
Michael Harms, Ph.D.
-----------------------------------------------------------
Conte Center for the Neuroscience of Mental Disorders
Washington University School of Medicine
Department of Psychiatry, Box 8134
660 South Euclid Ave.Tel: 314-747-6173
St. Louis, MO 63110Email: [log in to unmask]
On 5/21/16, 3:54 PM, "FSL - FMRIB's Software Library on behalf of Antonin
Skoch" <[log in to unmask] on behalf of [log in to unmask]> wrote:
Dear Matt, Michael,
thank you for your contribution.
Here is the relevant post from 3/2010 by Saad Jbabdi suggesting NOT to
stack/concatenate the data for BEDPOSTX.
https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind1003&L=FSL&D=0&1=FSL&9=A&
J=on&K=2&X=CBB60236BC562DF50E&Y=ansk%40ikem.cz&d=No+Match%3BMatch%3BMatches
&z=4&P=165079
Conversely, averaging of the data effectively changes distribution from
Rician to non-central chi as we discussed here:
http://community.mrtrix.org/t/anatomically-constrained-tractography-using-o
df-from-bedpostx/189/6
Would not this alteration of noise distribution have any spurious
consequence on validity of Bayesian inference on diffusion orientations in
BEDPOSTX?
With recent protocols we acquire data with 64 unique directions, but we
have quite large amount of data from previous studies acquired by 2x30
directions ("half-sphere" diffusion encoding). I would like to learn what
method of processing is optimal for these data.
Regards,
Antonin Skoch
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