My question arises because I recall reading a while ago that there was some assumption that the first b0 and first diffusion weighted volume should be collected close in time because of some assumption that there was no movement between these two volumes?
First instance, if we have a long example card and we first collect a single "blip-up" b0. Then, at the end of the example card, we collect a "blip-down" diffusion scan (with another b0). Assuming there is a decent deal of time/movement between the two b0s. If we:
1) run topup with the "blip-up" b0 first, followed by the "blip-down" b0 which might have significant movement between the two
2) run eddy with the outputs from topup and the "blip-down" diffusion scan
The outputs from topup/eddy will be aligned to the "blip-up" b0 scan, but susceptibility corrected. Is this correct? And is there any issue with there being a decent amount of rigid body motion between the "blip-up" and "blip-down" b0? Assume for now that we've already collected this data and can't change anything...
Thanks,
-Justin
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