They look pretty similar to me. A difference of about 0.0000000000000001 is pretty small really, and is attributable to rounding errors. Try evaluating the following in MATLAB: 1.0000000000000001 - 1 Best regards, -John On Tuesday 24 March 2009 19:04, Xu, Ben (NIH/NINDS) [E] wrote: > Hi, > > I have a question about the realignment parameters saved after > performing "Realign and Unwarp" with SPM5. > > I realigned two sessions (i.e., scan runs) using the default setting > with the first image of the first session as the reference image. I > performed realignment in two ways: > > Method 1: Included all the volumes in both sessions. > > Method 2: Included only the first volume for the first session (Session > 1), but all the volumes in the second session (Session 2). > > I was expecting the realignment parameters for Session 2 to be identical > or near identical with both realignment methods. However, this is not > what I got (see attached image). With Method 1, the realignment > parameters for the first volume (row 1 in the upper table of the > attached image) are almost all 0s except for the second column. But, > with Method 2, the realignment parameters for the first volume (row 1 in > the lower table in the image) are quite different from the results of > Method 1, although the rest looked almost identical. Why is there such a > difference for volume 1? Is it expected? > > Thanks much for your help. > > Ben > > -----Original Message----- > From: John Ashburner [mailto:[log in to unmask]] > Sent: Tuesday, March 24, 2009 1:57 PM > To: [log in to unmask] > Subject: Re: [SPM] Dartel Normalization of fMRI data > > If you have SPM8b (latest updates), then you should find this much > easier, as there is now an option to spatially normalise (and spatially > blur) fMRI to MNI space (as it incorporates an additional affine mapping > between DARTEL template and MNI template). I haven't had a chance to > update the user guide for DARTEL yet, but it should be reasonably > straightforward to use. > > I expect that the t stats should be increased, and look forward to any > feedback on whether this is the case. > > Best regards, > -John > > On Tuesday 24 March 2009 16:22, Amir Tahmasebi wrote: > > Dear John and SPMers, > > > > I am trying to use DARTEL for normalization of fMRI data. I have > > looked at "how to use DARTEL for normalizing fMRI con maps?" thread > > but it is not exactly what I was looking for. > > > > I was wondering how should I use the outputs of DARTEL ("u_rc1*.nii" > > and > > "Template_6.nii") to normalize my fMRI data which is already > > coregistered to the corresponding structural data. > > > > Thank you, > > Amir