Multi-echo fMRI support in 4.8.0
Markus Handal Sneve
The 4.8.0 release announcement mentioned multi-echo support for fMRI preprocessing.
Department of Psychology
Glasser, Matthew
That is correct. Also SBRef (--fmriscout) is a concatenation of the SBRef echos. Perhaps Burke after returning from vacation can make these things clearer in the documentation.
Note that we were disappointed with our multi-echo experience. We had hoped to find that multi echo produced better data than single echo, but this was not the case when we tested them head-to-head with a carefully matched protocol and optimized preprocessing. The multi-echo data were not bad, they just weren’t better than matched single echo data in terms of functional CNR (at least at the 2.4mm isotropic, TR=1000ms spatial and temporal resolution target that we set). Some of the literature out there was not entirely forthcoming about their MRI protocols and once the actual protocols were obtained it was found that certain unmatched protocol settings favored multi-echo over single echo but were not properly disclosed. As it stands currently, they are quite a pain to acquire on Siemens XA software, so we have dropped the idea for now.
Matt.
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Andre Zamani
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Glasser, Matthew
I would have to look again to find everything, but the big one was the reported resolution was 2.4mm isotropic, but in fact there was a reduced resolution in the phase direction (which increases SNR, but reduces actual resolution).
Matt.
Andre Zamani
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Glasser, Matthew
I can tell you what we did. We kept everything the same except for the TE and the required acceleration (MB=4xIPAT=1 vs MB=6xIPAT=2). We used the same acceleration scheme as in the paper.