Hi, Matt;
You are right. The FA map created with the mean image is less noisy.
Thanks
Jiansong
On Jan 20, 2008, at 2:42 PM, Matt Glasser wrote:
> The mean will have better SNR than the individual scans. You could do
> something like this to motion correct your data and get the mean:
> fslmerge -t big4d <data1> <data2>
> eddy_correct big4d big4d_corr 0
> fslroi big4d_corr av1_corr 0 <# of volumes in a single average>
> fslroi big4d_corr av2_corr <# of volumes in a single average> <# of
> volumes
> in a single average>
> fslmaths av1_corr -add av2_corr -div 2 <data>
>
> These commands merge the two averages into a single file for motion
> correction, then split out the motion corrected averages, and then
> get the
> mean.
>
> Peace,
>
> Matt.
> -----Original Message-----
> From: FSL - FMRIB's Software Library [mailto:[log in to unmask]] On
> Behalf
> Of Jiansong Xu
> Sent: Sunday, January 20, 2008 2:31 PM
> To: [log in to unmask]
> Subject: [FSL] DTI-- mean of two runs
>
> Dear Friends:
>
> I'm using FSL (FDT) to analyze DTI data acquired with a Simens Trio 3
> T scanner. Each subject had two scans with same parameters. My
> question is: is the mean image of the two scans better than either
> one of the two scans? If so, how to get the mean of the two images?
>
> Best
>
> Jiansong
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