Dear all,
I really need some help about a strange output made by topup+eddy.
I'm working for the first time with a GE scanner and I'm trying to fix my old preprocessing pipeline, which did very well with Philips and Siemens scanners, for this new tomograph. I've acquired the two sequence needed for topup (one RL and the other one LR), picked up the informations about the Echo Spacing (EPS) and the Echo Train Length (ETL), and I've also verify that the bvecs are distributed uniformly on the sphere. Respect with my older sequences this new one seems to have a very short ETL (only 48 echos), while the Echo Spacing is similar (0.684 ms).
The problems is that the distortion worsened with the application of topup, like there are problems with my acquisition_parameters matrix or the b02b0.cnf, but I really don't know how to fix this. Can the short ETL be the "guilty"?
I really hope that someone will give me a useful hint.
Chiara
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