Hi - if you are doing a custom registration, then I recommend generating a mask for each standard-space 4D dataset, and then combine across all the masks taking the intersection of then. Both steps very easy with fslmaths. Cheers. On 30 Apr 2013, at 19:03, Monty Waite <[log in to unmask]> wrote: > I am running MELODIC with a custom registration for 3 subjects - have run all the single level analyses and run updatefeatreg/featregapply to take my registrations into standard space for the 3 subjects who need custom registrations. > > Having a little difficulty with the masks though - I understand that to run a group concat, I need to create a custom mask using fslmerge of all subjects? Is this necessary and if so, could the custom registrations be the problem as cant seem to do this - get this error: > > Error in size-match along non-concatenated dimension for input file > > Thanks in advance > > Monty > --------------------------------------------------------------------------- Stephen M. Smith, Professor of Biomedical Engineering Associate Director, Oxford University FMRIB Centre FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 222726 (fax 222717) [log in to unmask] http://www.fmrib.ox.ac.uk/~steve ---------------------------------------------------------------------------