With the existing SPM software, I would go for option 1.
In a few hours, there will be a new set of updates for SPM, which will include
a DARTEL toolbox for warping groups of subjects to the shape of their
average. You may find this useful. It first needs the anatomical data to be
processed by the SPM5 segment button though (in order to import into a form
suitable for estimating the deformations). Note also that the end results
are not in MNI or Talairach space, but are in alignment with the average
brain shape, so a bit of extra fiddling (via the Deformations utility) is
likely to be needed in order to get the data into a form where you can report
your blobs in MNI coordinates. Nobody has yet applied it to functional data,
but it does produce much cleaner VBM analyses (e.g. ventricular volume
differences do not cause the insula to light up). Also note that DARTEL is
intended for advanced users. There is some documentation in the manual and
via the user interface, but not that much. Other documentation is in a
NeuroImage paper, and also in a manuscript that I'm currently writing.
Best regards,
-John
On Tuesday 16 October 2007 09:05, Nicola> <Canessa wrote:
> Dear experts,
> we are using SPM5 to compare patients vs. controls with fMRI. Our patients
> do not have gross anatomical abnormalities (this is one of the exclusion
> criteria). Yet, since the mean-age of both patients and controls is about
> 43 ± 8 (a little bit elder than the volunteers from which the MNI template
> was created) we are wondering whether we should use a specific template for
> normalization, and we are trying to distinguish among 3 options:
>
> 1) to run the classical pre-processing and simply taking the deformation
> parameters for normalization from the segmentation of the individual T1
> images (coregistered to the mean of the realigned functional images). In
> this case, one further option would be to use the "no priors" option of the
> VBM-toolbox 5.1
>
> 2) to search for an age-specific template. Provided that such templates do
> exist/are available somewhere, probably this would be the option for the
> best normalization as possible, yet the results would not be in the MNI
> space, and thus they could not be directly compared with those from other
> studies. Therefore, I would be inclined to discard this option.
>
> 3) to create an ad-hoc-template, but since we don't have hundreds of images
> (just 15 patients and 15 controls) this does not sound feasible
>
> Any suggestions/criticism about these options?
>
>
> Many thanks in advance,
> best wishes,
> nicola
>
> ***************************
> Nicola Canessa, Ph.D.
> CRESA, www.cresa.eu
> San Raffaele Research Institute,
> Via Olgettina 58,
> 20132, Milano, Italy
> +39-02-2643-4888
> [log in to unmask]
> ***************************
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