On Nov 7, 2017, at 7:14 AM, Douglas N Greve
<gr...@nmr.mgh.harvard.edu <mailto:gr...@nmr.mgh.harvard.edu>> wrote:
On 11/06/2017 12:03 PM, lanbo Wang wrote:
Dear experts,
I have two questions about hemisphere analysis:
1) When I run left-right hemisphere paired t-test, can I add age as
covariate? If use fsgd to add covariate, to this paired t-test
analysis, how to make the fsgd table?
use this one-group, one-covariate example
https://surfer.nmr.mgh.harvard.edu/fswiki/Fsgdf1G1V
2) I want to reorganize the hemisphere from left-right to
symptom-nosymptom according to body symptom side record and compare
different between symptom hemisphere and nosymptom hemisphere. Can I
use freesurfer to do it?
Yes, though it is a little tricky with multiple ways, each complicated
in its own way.
1. Create your own design matrix. You can use the one created by
mri_glmfit to start. Assuming you want symptomHemi-nosymptomHemi, then,
in each subject whose symptomHemi is rh, multiply its line in the design
matrix by -1. Then pass this design matrix to mri_glmfit with --X
instead of passing an FSGD file.
2. Load the output of mris_preproc into matlab, eg, y =
MRIread('y.mgh');, then change the sign as in #1 above, eg,
y.vol(:,:,:,10) = -y.vol(:,:,:,10); and so on for each applicable
subject. Then save the data with MRIwrite(y,'new.y.mgh');, then run
mri_glmfit as normal with the new file.
3. Run mris_preproc for each subject separately to generate an
lh.lh-rh.thickness.sm00.subject10.mgh file. Then change the sign as in
#1 above with
fscalc lh.lh-rh.thickness.sm00.subject10.mgh mul -1 -o
lh.lh-rh.thickness.sm00.subject10.mgh
Then run mri_concat to concatenate all the subjects together in the same
order as they are listed in the FSGD file, then use this stack as input
the mri_glmfit
Thanks for your patient and help.
All best,
Lanbo Wang
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Douglas N. Greve, Ph.D.
MGH-NMR Center
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