I think there is a lot in the archives on this. Assuming you need the usual asymmetrical template, I would suggest:
1. take representative subjects (controls of similar age, or a mix of patients and controls)
2. 12 should be enough, you might get away with 10 or so, the more the better (probably)
3. "coregister only" each subject's FDG PET to their MRI
4. "SEGMENT" (SPM5, SPM8) their MRI - this will create a *_seg_sn.mat file
5. Use the *_seg_sn.mat file to write the PET into MNI/ICBM152 space -> wPET ("normalise write"; you may want to adjust the bounding box so the resulting images have an MNI/ICBM152 matrix; this can be very useful if you switch between software packages)
6. Create a soft mean of all wPETs (see archives)
7. Smooth the result by about 8x8x8 mm
- and there you go!
If you only get say six subjects with PET and MRI, and six with PET only, you could do the above for the six MRI+PET ones, create an intermediate template, and then do a PET-PET normalisation for the other six, repeating the soft mean + smoothing step - but the result will be more biased towards the first six ones.
Hope this helps, and good luck,
From: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] On Behalf Of Vilardi Ignazio
Sent: 18 June 2009 11:25
To: [log in to unmask]
Subject: [SPM] FDG-PET template
looking at some publications, the PET template provided with SPM may be not ideal for FDG studies, as it was created with 15O-H2O.
If I have the possibility to create an in-house FDG template, how many volunteers do I need? The age is important? I need also the MRI for each volunteer?
Thanks for your replay