Dear List
I've been following the recent discussions about how best to identify the
anatomical regions from their MNI or Talairach co-ordinates. I use SPM96 in
MEDx for analysing SPECT scans, but I don't have the option of coregistering
the SPECT scans with structural scans from the patients. I am therefore left
with the options of using the PET template in the spatial normalisation stage
and converting the MNI co-ordinates to Talairach co-ordinates (for the
Talairach Daemon) and/or superimposing the blobs onto the (MNI) MRI scan that
comes with SPM96.
MEDx will enable me (outside SPM) to make a user-defined SPECT template
registered to the Talairach atlas (rather than MNI space), and I wanted to ask
how appropriate this might be.
What I was proposing to do was:
1] take a group of e.g. 32 normal SPECT scans (2 scans each from 16 healthy
volunteers)
2] in the SPM realignment stage set 1 Subject/ 32 images then realign them all
to the first image of the series
3] make a mean image of the realigned images (using a MEDx module outside SPM)
4] in SPM realign this mean image to the PET template to ensure correct
orientation re the AC-PC line etc.
5] register the realigned mean image to the Talairach Atlas (again, using a
MEDx module outside SPM). The voxel sizes can all be set appropriately eg
2x2x4mm.
This should result in a user-defined template for use in the spatial
normalisation stage of SPM that should result in accurate Talairach
co-ordinates.
Now, I understand the issues around the 'what do you want Talairach
co-ordinates and Brodmann areas for in the first place?' argument. But if I
DID want Talairach co-ordinates and Brodmann areas are there obvious flaws in
the above thinking? And do you think there would be any difference in accuracy
in doing the above and, say, using the PET template (MNI) and trying to
identify regions from the MRI scan that comes with SPM96?
Thanks for your time.
Peter
----------------------
Dr Peter Talbot
Department of Mental Health
Queens University Belfast
Whitla Medical Building
Lisburn Road
Belfast BT9 7BL,
NORTHERN IRELAND, U.K.
Phone: +44 (0)28 9027 2166
Phone: +44 (0)28 9033 5791
Fax: +44 (0)28 9032 4543
Email: [log in to unmask]
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