first, make sure you use the Fieldmap Toolbox *version 2*.
You should load the phase difference map and one of the magnitude images (I
think it does not matter which one, but hopefully someone will correct me
if this is not the case). Furthermore you have to know the tow TEs and the
EPI readout time. With this information, everything should be very
straightforward - at least it has worked for me. There is a manual
accompanying the toolbox, which lists all the different input option and
the required information.
Jaclyn Billington wrote:
> Dear users,
> I'm using the FieldMap toolbox for the first to to create vdm images for use
> with realign and unwarp in spm5.
> The toolbox seems to require either 2 images (single phase and single
> magnitude) or 4 images (long/short TE phase and long/ short TE magnitude).
> The fieldmap data I've acquired (on a 3T siemens trio) comprises of: long TE
> phase, long TE magnitude and short TE magnitude images.
> I'm not sure if I should be loading both the long echo time images as a
> single phase/magnitude image (effectively loading them in the required short
> TE data input fields) or whether I should have an extra short TE phase image.
> I've tried the former and the resulting fieldmap looks okay, but I'm not
> sure if that is the correct procedure.
> I'd be very grateful if anyone could advise on this issue.
> Thank you.
> Regards, Jac
Jan Gläscher, Ph.D. Div. Humanities & Social Sciences
+1 (626) 395-3898 (office) Caltech, Broad Center, M/C 114-96
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