We've had two pilot sessions so far, each with a different participant and somewhat different sequences. We're most interested in task fMRI, but that's tricky at the moment since the scanner doesn't (yet) have a way to present stimuli, nor to record responses. Eventually I want to do sequence comparisons with the reward-possible DMCC proactive Cued Task-Switching paradigm (and probably other tasks), like in my OHBM 2023 poster. But to get started I asked the second pilot participant to do a self-paced version of the HCP Motor task: blocks of right finger tapping, left finger tapping, right toe wiggling, left toe wiggling, tongue moving, with a bit of rest in between and a few deep breaths before and after each movement block to serve as onset/offset markers. (I'm not going to discuss the movement analysis parts yet, but so far I'm encouraged.)
Both pilot sessions included a pair (PA/AP) of runs with an acquisition similar-ish to what we used in the DMCC at 3T: 2.4 mm iso voxels, MB4, TR 1.2 s. But the 7T allows more acceleration, so they added in-plane acceleration (GRAPPA 2) and collected 4 echoes instead of just 1.
Below are the realignment parameters (from the fmriprep derivative _desc-confounds_timeseries.tsv files) for those runs from the two participants we've had so far. In both cases the grey vertical lines are at one-minute intervals; the first participant (TB7T1)'s runs were about 10.5 minutes and he alternated periods of regular and slow/deep breaths; the second participant (TD7T1)'s runs were about 6.5 minutes each and he did the blocked breathing-motor task.
TB7T1 clearly has much more apparent motion than TD7T1; the periods of regular and deep breathing are obvious, not only in the realignment parameters but also in movies of the BOLD run. TB7T1_run-44_echo-1_bold.avi is the "rawdata" (before preprocessing) version of echo 1; TB7T1_run-44_space-MNI152NLin2009cAsym_desc-preproc_bold.avi is after preprocessing (with fMRIPrep 25.1.0 using Tedana to optimally combine the echoes). The brain sort of looks like it's "jumping" with the breaths in the raw movie; perhaps more like expanding and contracting in the preprocessed version.
The TB7T1 participant is the same individual as in some of our previous acquisition tests (at 3T); clearly, using 7T doesn't mean we can forget about apparent motion. ... I wouldn't have forgotten about apparent motion regardless since it's a favorite topic of mine, as is probably obvious since I'm starting off this (hopefully) series of posts about our 7T piloting with it.
Each of these sessions included multiple different acquisition sequences; in all cases TB7T1 had more obvious apparent motion than did TD7T1. TB7T1 run 28 had the largest apparent motion; it also had smaller voxels and a longer TR than the other examples.
Finally, the TB7T1 run 44 motion is also striking in the greyplot version created by fmriprep (left); TD7T1 run 24 is below, right:
