I have a query about the eddy current correction scheme in FSL.
As part of eddy current correction, my understanding is that each
diffusion-weighted volume is linearly aligned to a reference volume, where
the reference volume is typically chosen as an average over all the b=0
volumes acquired.
In aligning a d-w volume to the ref vol, it seems we also need to re-align
the gradient vectors accordingly. In particular, the gradient vectors
should be re-aligned according to the matrix taking d_w to ref. Given that
the d_w to ref matrix is not necessarily unique across all d-w volumes, it
also seems each d-w volume has its own unique set of re-aligned gradient
vectors. Specifically, a common set of gradient vectors cannot be assigned
to all d-w volumes.
Does the eddy current correction scheme in FSL perform re-alignment of the
gradient vectors? My guess is that this kind of re-alignment is not really
a big deal so it has not been implemented.
Andrew
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