Hello,
the discussion about study specific templates is about as old as spm,
and is still not easily answered. There are three main lines of arguments:
- the further away your population is from the standard template, the
more it makes sense to make your own template. Hence, it is meaningful
to use an appropriate template for children or older adults.
- the larger your group is, the more it makes sense to make your own
template. Even for a group of young and healthy adults, if you have
>>100, your own template will be more appropriate as you include (all
of) your own subjects, with your own scanner- and sequence-specific effects.
- the more your processing relies on the features provided by the
template, the more it makes sense to make your own template. This effect
has gradually gone down in the last iterations of standard segmentation,
then unified segmentation, then new segment, to the point that the
priors are only used to initiate segmentation in vbm8 (I hope I got that
last point right :) Therefore, the lower the effect of a template is in
the first place, the less important it is to create your own.
These are some basic ideas; what conclusion you draw from that is highly
dependent on where you are on each count. There is no absolute hard rule
on when to do what.
Cheers,
Marko
zao liu wrote:
> Dear SPM community,
>
> A study specific template is recommended in our ALS literature. So I am
> wondering how to create study specific template based on our patients
> and control subjects in SPM8 (VBM 8). I also came across email responses
> in SPM email list saying that it is not necessary to create study
> specific template in SPM5 so I am little bit puzzled. Any help would be
> greatly appreciated.
>
>
> Thanks
--
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Marko Wilke (Dr.med./M.D.)
[log in to unmask]
Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
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