you should always average your raw data.
noise exerts a greater effect on images with higher diffusion weighting
(less signal) so it is better to average first and then calculate the
tensor/bedpost parameters.
scott
Matt Glasser wrote:
> Why is that? Regardless, it is necessary to align your averages with some
> rigid body registration before averaging.
>
> Peace,
>
> Matt.
>
> -----Original Message-----
> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On Behalf
> Of Peter Kochunov
> Sent: Friday, October 31, 2008 10:42 AM
> To: [log in to unmask]
> Subject: Re: [FSL] DTI Average
>
> It would be safer to average the scalar output of the dtifit, rather than
> individual, diffusions-sensitized images.
> pk
> ----- Original Message -----
> From: "Departament de Psiquiatria i Psicobiologia Cli -nica UB Mundet"
> <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Friday, October 31, 2008 10:07 AM
> Subject: [FSL] DTI Average
>
>
> Hi, we would like to know how to average two or more DTI adquisitions in FSL
> software. Can you create an average image before preprocessing? Or you can
> only average the values you calculate from a ROI in a FA map (for example)
> of
> every adquisition from every subject after preprocessing?
>
> Thank you.
>
--
========================
Scott Kolbe
MS Imaging Group
Howard Florey Institute &
Centre for Neuroscience
University of Melbourne
VIC, Australia, 3010.
ph: +61 3 8344 1887
email: [log in to unmask]
website: http://www.neuroimaging.org.au/index.php?id=383
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