Dear list,
I am trying to use the fieldmap SPM5 toolbox to correct geometric
distortions for coronal slices of high resolution (2x2x2) 2DEPI data.
The 2DEPI acquisition (on a Philips Achieva MR scanner) is accelerated
with SENSE (eg, sparse K-space sampling) to decrease distortion. This
helps, but is not enough due to long readout in case of high-resolution
data. Phase encoding was in the LR direction. This is the only option,
because SENSE acceleration can't be done FH since most SENSE headcoil
does not have opposing coils in that direction.
Now I read in the manual that the Fieldmap toolbox is designed for axial
slices with phase encoding either AP or PA. Would it be possible to
tweak the fieldmap toolbox to do corrections for coronal slices the
right way? The only message I found with a similar question was:
http://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=ind04&L=spm&O=D&F=&I=-3&S=&P=306371
but unfortunately I could not find an answer...
I tried to simulate SENSE readout when acquiring the required phase maps
at 2 echo times by doubling voxel size in the phase encoding direction,
or by adding a 2nd shot. That seems to have worked.
Any help would be appreciated!
Cheers,
Bas
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Dr. S.F.W. Neggers
Division of Brain Research
Rudolf Magnus Institute for Neuroscience
Utrecht University Medical Center
Visiting : Heidelberglaan 100, 3584 CX Utrecht
Room B.01.1.03
Mail : Huispost B.01.206, P.O. Box 85500
3508 GA Utrecht, the Netherlands
Tel : +31 (0)30 2509609
Fax : +31 (0)30 2505443
E-mail : [log in to unmask]
Web : http://www.fmri.nl/people/bas.html
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