Hi David,
Here are a couple of thoughts, certainly other folks on the SPM mailing
list will have good ideas on this topic. I think it makes sense to
register a group of individual brains to a stereotaxic template with
approximately the 'average anatomy' of the group, especially if the
regional anatomy of the group differs systematically from that of young
adult normals (e.g. in the case of children, or AD patients), and
especially if nonlinear registration (warping) is used.
1. In our experience it is also easier to automatically register new
elderly brains to a template that more closely resembles them in
intensity and geometry than the young normal ICBM305 or a specific
individual brain dataset. Also if a template with the average intensity
and geometry for a group is used as a target for nonlinear registration
(warping), on average least distortion will be applied to the data that
is normalized to it. This is a little bit of formal discussion of this
on page 13 of this paper, because 'average distortion' can be quantified
in many ways:
http://www.loni.ucla.edu/~thompson/PDF/Framework01_v3.pdf
2. In terms of average elderly or average Alzheimer's disease brain
templates that you could use for your SPM analyses, there are a couple
that we have made that you are very welcome to try out. We usually do
PET-to-MRI rigid intrasubject registration first, and then use affine
and subsequently nonlinear mapping to carry the subject's MRI into the
average elderly brain template. We have found that it is also
advantageous to use a mean image template in which cortical features are
as well-resolved as possible, and appear in their mean geometric
locations, like the one in the little picture here:
http://www.loni.ucla.edu/~thompson/DisChpt.html
-- this way we have found that there is the best chance of accurately
registering cortical anatomy. There is a discussion of this here:
http://www.loni.ucla.edu/~thompson/disease_atlases.html
and in papers #10, #13 and #61 here:
http://www.loni.ucla.edu/~thompson/thompson_pubs.html
The template made in paper #10 is available in case you'd like to try it
out, here:
http://www.loni.ucla.edu/~thompson/AD/TEMPLATE/NEW_AFFINE_TEMPLATE/
as Atlas_2_new_affine.img, and there is also a version resliced
orthogonal to the long axis of the hippocampus:
hip_atlas.img
I hope this helps a little -- Good luck! - Paul
--
Paul Thompson, Ph.D.
Assistant Professor of Neurology, Dept. Neurology
UCLA Lab of Neuro-Imaging & Brain Mapping Division
4238 Reed Neurology, UCLA Medical Center
710 Westwood Plaza
Los Angeles, CA 90095-1769
[log in to unmask]
http://www.loni.ucla.edu/~thompson/thompson.html
http://www.loni.ucla.edu/~thompson/thompson_pubs.html
Normalizing AD PET and MRI
Date:
Thu, 15 Nov 2001 15:38:17 -0500
From:
"Kareken, David A." <[log in to unmask]>
To:
"[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>,
"[log in to unmask]" <[log in to unmask]>
Colleagues,
If I could take a moment your time...
I have noted all of your names in prior discussions on the SPM list
server
about normalizing patient data to a stereotactic template, but I haven't
found much since some time ago. I intend on collecting blood flow PETs
of
healthy normal elderly and AD patients (mild, early stage) and would
like to
compare activation in one group to another. I will have SPGR MRIs on
the
subjects, as well. Can someone tell me the latest thinking on the
stereotactic normalization of patients with atrophy and elderly, and the
potentially biasing effects of atrophy using SPM99?
Should I be creating my own template? I have seen reference to
co-registering the MRI with the PET first, normalizing the MRI, and then
applying the same normalization paramters to the PET. Is there a
preferred
way to go? Is there literature on this?
Thank you all for any help you can offer.
Best,
David
________________________________
David A. Kareken, Ph.D., ABPP
Board Certified Clinical Neuropsychologist
Assistant Professor & Director
Neuropsychology Section, Department of Neurology
RI 1773
Indiana University School of Medicine
Indianapolis, IN 46202
(317) 274-7327 (voice)
(317) 274-1337 (fax)
|