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Thanks. Jiansong On Jan 20, 2008, at 2:56 PM, Andreas Bartsch wrote: > Be aware that the two scans may actually have different diffusions > vectors applied to them (if these were specified XYZ and if you > angualted the slices). > Cheers- > Andreas > > -----Ursprüngliche Nachricht----- > Von: FSL - FMRIB's Software Library [mailto:[log in to unmask]] Im > Auftrag von Matt Glasser > Gesendet: Sonntag, 20. Januar 2008 20:43 > An: [log in to unmask] > Betreff: Re: [FSL] DTI-- mean of two runs > > 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