Maria,
I am not wholly sure what you mean by "choosing the middle volume". If
you manually select volume 63 as the reference image, then I would
assume that all values are provided with reference to that volume, for
all volumes as selected.
This should not be necessary, though, as spm provides the option to
internally generate a mean volume in a first pass of the realignment
procedure and then use that as the reference volume in a second pass (I
think the option is called "register to mean" under the "NUM passes"
option). This may be a safer option for you.
Cheers,
Marko
Maria Densmore wrote:
> Hello SPMers.
>
> Regarding fMRI Realignment
> when the middle volume(63) is chosen first (instead of the 1st
> chronological volume) how does that affect the realignment parameter
> order in the rp_*63*.txt file?
>
> Are the first set of 6 values representing the 63rd volume
> followed by the 1st volume->62vol->64vol->end ,
>
> in the order entered or in chronological order?
>
> Thanks in advance for the clarification.
> Maria
>
--
____________________________________________________
PD Dr. med. Marko Wilke
Facharzt für Kinder- und Jugendmedizin
Leiter, Experimentelle Pädiatrische Neurobildgebung
Universitäts-Kinderklinik
Abt. III (Neuropädiatrie)
Marko Wilke, MD, PhD
Pediatrician
Head, Experimental Pediatric Neuroimaging
University Children's Hospital
Dept. III (Pediatric Neurology)
Hoppe-Seyler-Str. 1
D - 72076 Tübingen, Germany
Tel. +49 7071 29-83416
Fax +49 7071 29-5473
[log in to unmask]
http://www.medizin.uni-tuebingen.de/kinder/epn/
____________________________________________________
|