Linda,
it is fine to use a custom template when processing an "unusual sample"
(i.e., not-27-year-old-Canadians :) However, you still have to bring all
subjects into some kind of standardized space, within which all of your
subjects then overlap.
Whether you call it MNI or something else is not that important, what is
important is how you define your target brain that you normalize to. If
you use a different target for each subject, then it will likely lead to
more inhomogeneity than if you use a single target brain (which is very
advisable also on statistical grounds). So you either normalize all your
subjects (I would recommend affine-only, but there are other opinions on
that) and average them, or use DARTEL, or use the TOM toolbox (PMID:
18424084).
Cheers,
Marko
Linda Solstrand Dahlberg wrote:
> Hi,
>
> I really hope someone can help me with this:
>
> We're currently doing a study using an adolescent subject sample, and we
> therefore want to normalise the data onto a template based on adolescent
> brains. however, we are having difficulties in the methods here.I know
> that *SPM8* use the MNI as the standard template, but how do I change this?
>
> In my attempts, I have tried to normalise (estimate) the T1 to the
> adolescent template, and then normalise (write) the T2's onto the newly
> normalised T1's for each subject, but when I then check the images, they
> all look slightly off and a bit skewed.
>
> Any ideas and advice will be greatly appreciated!
>
> Best wishes,
>
> Linda S. Dahlberg
--
____________________________________________________
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/
____________________________________________________
|