Indeed - you don't just want to do pairwise subtraction Abi, it's better to do sub-TR timing-adjustment on the tagged and control data before subtraction - if you look in the latest version of FEAT in FSL you'll see options for easy preprocessing of ASL data. You would then be able to use the normal methods for transferring FEAT data into FreeSurferSpace.
Cheers, Steve.
On 27 Nov 2006, at 17:47, Doug Greve wrote:
We don't have an MC program. You can try running FSL's FLIRT or AFNI's 3dvolreg. As for analysis, you should be able run
mri_concat --paired-diff --mean inputaslvolume outputvolume
I've never actually tried it like this, but it should work.
doug
On Mon, 27 Nov 2006, Abi Gopal wrote:
Hi all
I have collected some raw Arterial Spin Labeling (ASL) data. I would like to use freesurfer to create perfusion maps of this data. Is it possible to take the raw data, motion correct it, perform a pairwise subtraction, and then average all the subtractions to create a mean perfusion map? Please let me know if you have ideas on how to do this sort of thing.
Thanks Abi
-- Douglas N. Greve, Ph.D. MGH-NMR Center greve@nmr.mgh.harvard.edu Phone Number: 617-724-2358 Fax: 617-726-7422
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