Because my subjects are aged patients with possible brain structural changes, I want to perform DARTEL normalization rather than default spatial normalization in SPM8 so as to have a better spatial normalization.
All EPI images were adjusted for timing differences between slices, unwarped using field maps, realigned and re-sliced to correct for motion artifacts (producing rxxx.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).
Below is my procedure for DARTEL normalization and I hope someone could help to confirm my procedures:
Images = Coregistered T1WI
Grey matter/white matter/CSF = Native space
[This process produced a xxx_sn.mat file as well as c1xx, c2xx, c3xx files corresponging to GM, WM, and CSF]
(2). DARTEL tool, Initial import
Parameter files = xxx_sn.mat
GM, WM, CSF: Yes
Voxel size: 1.5
[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 a series of template files, with the last one called template_6.nii]
(4). Normalize into MNI space
DARTEL template: template_6.nii
Flow fields = u_rc1xx
Images = rxxx.nii
Preserve = Preserve Concentrations ("no modulation")
[This process produced swrxxx.nii but also Template_6_2mni.mat]
Are my procedures correct?
However, the voxel size in swrxxx.nii is 1.5x1.5x1.5. If I want to get a MNI standard space with 2x2x2 voxel size, how should I do?
Also, (4) performed not only normalization but automatically smoothing process...
Thanks in advance. Mike