Hi,
I've posted a similar message before but still unclear about the details so here I describe my question as a whole and hope some experts could help.
In my fMRI experiment, my subjects are old aged patients and age- and sex-matched healthy controls. They received EPI functional scanning when they performed a cognitive task. My aim is to compare brain activations between both groups.
Here is the preprocessing procedure for each subject’s data: All EPI images were adjusted for timing differences between slices, unwarped using field maps, realigned and re-sliced to correct for motion artifacts (producing auxxx.nii). The resulting mean EPI was co-registered with the subject's T2-weighted image, which in turn was aligned with the T1-weighted image (that is, T1WI has been coregistered to EPI; designated as coregistered T1WI). Before first-level model specification, I would also perform spatial normalization and then smoothing. For spatial normalization process, since patients’ disease and advanced age may be accompanied with brain structural changes, I think DARTEL normalization would be more suitable than default spatial normalization in SPM8 so would like to perform DARTEL spatial normalization in single subject's data preprocessing.
Below is my procedure for DARTEL spatial normalization:
(1). Segment
Images = Coregistered T1WI
Grey matter/white matter/CSF = Native space
[This process produced a seg_sn.mat file as well as c1xx, c2xx, c3xx files]
(2). DARTEL tool, Initial import
Parameter files = seg_sn.mat
GM, WM, CSF: Yes
[This process produced rc1xx, rc2xx, rc3xx file]
(3). DARTEL tool, run DARTEL
Images: rc1xx, rc2xx, rc3xx
[This process produced u_rc1xx, u_rc2xx, u_rc3xx file, and template_6.nii]
(4). Normalize into MNI space
DARTEL template: template_6.nii
Few subjects
Flow fields = u_rc1xx
Images = auxxx.nii
Preserve = Preserve Concentrations ("no modulation")
Voxel size=2 2 2
[This process produced swauxxx.nii]
Then I use swauxxx.nii for subsequent first-level model specification.
My question is:
(1). Can I use DARTEL normalization here to replace default low-resolution spatial normalization in each subject’s fMRI data preprocessing stage to enhance spatial normalization?
(2). If yes, are my procedures above correct?
Thanks a lot. Mike
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