Hi CIara,
> Ive began to collect field maps and plan to use them with spm8
> any direction at what point they are slotted in to the registration
> process and how?
As you likely do, I also find the option is less clear to find than one
would hope :) as it is a bit hidden: when using realign and unwarp, you
can proceed with and without a fieldmap. With a fieldmap, EPI
distortions will (well, partially) be corrected for, while without, the
option will still do some unwarping, namely the motion*B0 interaction.
You will find more background on that in Andersson, Hutton et al., 2001
(Neuroimage 13:903-919). In order for this EPI unwarping to work, you
need to generate a voxel displacement map, which is done using the
fieldmap toolbox. In order to set the right parameters here, contact
your MR physics department ;)
Hope this helps,
Marko
--
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Marko Wilke (Dr.med./M.D.)
[log in to unmask]
Universitäts-Kinderklinik University Children's Hospital
Abt. III (Neuropädiatrie) Dept. III (Pediatric neurology)
Hoppe-Seyler-Str. 1, D - 72076 Tübingen
Tel.: (+49) 07071 29-83416 Fax: (+49) 07071 29-5473
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