We could create a pediatric reference template by warping the adult one to a
pediatric space - would this be helpful?
The adult EPI template could be warped into pediatric space using the
spatial transformation parameters from warping the adult T1 to the available
CCHMC2 children's T1 template (or study-specific T1 anatomicals).
I'm unclear whether a pediatric template will improve spatial normalization
or whether it will simply localize the results more accurately.
Cheers,
Paul
On Tue, 24 May 2005 23:02:57 -0700, Russ Poldrack <[log in to unmask]> wrote:
>Agreed - if you are focusing on a single age group, then using a age-
>group-specific atlas seems like a good idea.
>cheers
>russ
>
>On May 24, 2005, at 10:51 PM, Marko Wilke wrote:
>
>> Hi Russ,
>>
>>
>>> I would like to make an argument in favor of using the adult
>>> template for normalization of kids' data, and against using age-
>>> specific templates. If you use different templates to normalize
>>> different groups of kids, then there will be systematic
>>> differences between the age groups and your comparisons between
>>> age groups are necessarily confounded with anatomical differenecs.
>>>
>>
>> I fully agree: if one wishes to make inferences about different age
>> groups in one study, one should use the same template for all of
>> them, for exactly the reason you specified. However...
>>
>>
>>> If you use the adult template then there will be increased noise
>>> in the normalization, but since the target is the same for all
>>> subjects the age comparison is not necessarily confounded.
>>>
>>
>> This is not only true if the adult template is used but also if ONE
>> pediatric template is used for each study (I hope I never advocated
>> using different templates within one study). In addition, a
>> pediatric template will be closer to the group under investigation
>> in shape and tissue composition (most important for an optimized
>> processing stream and if young children are included), which is why
>> I think that using a pediatric template still beats using an adult
>> one.
>>
>>
>>> Also, note that Steve Petersen's group has published a couple of
>>> papers in NeuroImage (Kang et al., 2003; Burgund et al., 2002)
>>> which have shown that normalization of kids' data to an adult
>>> template actually does quite a good job.
>>>
>>
>> I have read these and I agree that the results look very decent.
>> However, when I compare my results from both approaches, I very
>> much favor the pediatric reference data.
>>
>> Best from Tuebingen,
>> Marko
>> --
>> =====================================================================
>> 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
>> =====================================================================
>>
>>
>
>---
>Russell A. Poldrack, Ph.d.
>Assistant Professor
>UCLA Department of Psychology
>Franz Hall, Box 951563
>Los Angeles, CA 90095-1563
>
>phone: 310-794-1224
>fax: 310-206-5895
>email: [log in to unmask]
>web: www.poldracklab.org
>
>
|