Dear all,
I have a bunch of DTI-datasets from patients who have undergone functional
hemispherectomy. Since I want to run voxelwise analyses, I need to
normalize these highly deformed brains. It seems that the normalization of
T1 is affected by a field bias (i.e. occipital hyperintensities and frontal
hypointensities). I, therefore, want to correct the field bias. There are
four quesions I have:
question1. When I generate a bias field by means of FAST, it turns out to
be affected by the low signal in the lesioned hemisphere. Now I wonder
whether I can run FAST with the lesion masked out?
question2. Is it possible to create some kind of average field-map out of
several unlesioned-brains (who have been scanned with the same sequence and
the same scanner) bias-fields (generated by means of FAST) and apply this
on the lesioned ones?
question3. Should I use segmentation with FAST to remove the CSF before
creating the bias field?
question4. Is there any advantage in using mfast (e.g. with a T2) while
creating this bias-field (if the bias field is only noticeable on the T1)?
Any help on this is highly appreciated.
Thanks in advance!
Best,
Conrad
Conrad C. Prillwitz
Universitätsklinikum Bonn
Klinik für Epileptologie
Sigmund-Freud-Straße 25
D - 53127 Bonn
Germany
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