Hello --
I'm trying to perform distortion correction on EPI data
collected on a 3T Siemens scanner. I have installed the CBU software
and have it working with the sample "Siemens" phantom data. However,
my attempts to apply the method to my data have been unsuccessful. My
magnitude and phase images seem to have the same properties (e.g.,
range of values) as the files in the sample data, but when I perform
the correction it munges my EPI from this:
to this
.
Looking at the intermediate images, it looks like things go
wrong at the creation of the "rpm_ac_rot_*" files. I've tried
tinkering with a number of settings but cannot escape this
"quartering" of the brain effect. Has anyone out there seen anything
like this before?
I would be especially grateful if someone who uses the Siemens
field map technique with the CBU software could take a look at my
field map files and point me in the right direction. For that matter,
I am not wed to the CBU method, and would also welcome any specific
advice on how to get these fieldmap files to process through the FSL
Fugue code.
Thanks very much.
Geoff
--
Geoffrey Karl Aguirre, M.D., Ph.D.
[log in to unmask]
Assistant Professor of Neurology
Hospital of the University of Pennsylvania
Center for Cognitive Neuroscience
Philadelphia, PA
|