You can still average the data if you also rotate the bvecs and then
average them too. Averaging will result in faster bedpostX processing
too.
More importantly though, you ideally would acquire 60 unique directions
instead of 30x2, as this will help you find fiber crossings better.
Peace,
Matt.
On 5/20/16, 3:00 PM, "FSL - FMRIB's Software Library on behalf of Harms,
Michael" <[log in to unmask] on behalf of [log in to unmask]> wrote:
>
>Hi,
>Iım pretty sure that it is quite ok to simply stack (concatenate) the
>datasets together. Perhaps you could provide the link to the post(s) that
>suggested that wasnıt the case.
>
>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 5/20/16, 2:54 PM, "FSL - FMRIB's Software Library on behalf of Antonin
>Skoch" <[log in to unmask] on behalf of [log in to unmask]> wrote:
>
>Dear FSL experts,
>
>I have data acquired with 30 directions and 2 NEX (originally intended to
>increase SNR). I am looking for a way how to correctly process them. In
>2010 there was a post that for BEDPOSTX is in this case better to average
>data than stack the data together unaveraged, since in this case ARD on
>the secondary fibres does not work properly.
>
>But averaging, apart from the fact that it is not effectively possible to
>rotate b-vectors after motion correction, changes also the distribution of
>noise in the data (it is no longer Rician).
>
>As the original post is quite old and things with BEDPOSTX implementation
>could have changed, I would like to ask if Is it still valid for recent
>versions of BEDPOSTX (FSL 5.0.9), that it does not work correctly for
>stacked data with replicated b-vectors in one dataset?
>
>Thank you very much in advance for the clarification.
>
>Regards,
>
>Antonin Skoch
>
>
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