I think the correct terminology is b0 field map. A gradient field usually
refers to something else. You would do field map correction as a part of
preprocessing. This paper lays out how we did this in the HCP:
http://www.sciencedirect.com/science/article/pii/S1053811913005053
Peace,
Matt.
On 6/12/13 2:20 PM, "Gillian Cooke" <[log in to unmask]> wrote:
>Hi Steve,
>
>I'm sorry if I wasn't clear first time around. We want to use our
>gradient field maps to correct for distortion in the signal - and since
>we are also going to use melodic to clean up our data before running our
>first levels and groups analysis we were wondering at what point in the
>processing stream it is best to use the gradient field map - when we run
>the melodic, or after when we run the first levels on the denoised data?
>Or should it be used at both points?
>
>Does that make any sense?!
>
>Gill
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