I think the realignment is to the first image selected in the 4D series, that is the order they are selected in matters. You can order the volumes in any way including reverse order. Adjusting this could mess up the interpretation of the realignment file, for instance if the 'real' order is from volume 1 to volume 300 then any functional task would be in that sequential order. It is usually best to include the additional registration to mean.
Simon
-----Original Message-----
From: SPM (Statistical Parametric Mapping) <[log in to unmask]> On Behalf Of Catarina Rua
Sent: 04 October 2018 10:01
To: [log in to unmask]
Subject: [SPM] spm realign to last volume of the time series
Dear SPMers,
I would like to use SPM's realign function to realign an fmri time series to the last acquired volume. Since the fags we can select are either to realign to the mean of the time series or the first image of the time series, can I simply flip the data having the last volume acquired as volume 1, then realign using: flags.rtm = 0; and then flip back the time series?
Is this procedure isn't very neat, would you advice some other method?
Thank you very much in advance.
Best wishes,
Cat
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