Fmap-less SDC output from fmriprep

Summary of what happened:

I used fieldmap less SDC for my rsfMRI data. However, the output looks a bit weird. There seems to be some significant distortion along with ventricles, and i think it came from the fmap Hz created from the pipeline. I would appreciate if anyone can help me to evaluate this - is this normal to see some loss of signals in the center of the brain?

Thank you!!

Command used (and if a helper script was used, a link to the helper script or the command generated):

singularity run --cleanenv \
    --bind ${bids_root_dir}:/data:ro \
    --bind ${out_dir}:/out \
    --bind ${work_dir}:/work \
    --bind ${FS_LICENSE}:/freesurfer_license.txt \
    /home/groups/vhenders/simg/fmriprep.sif \
    /data /out participant \
    --use-syn-sdc \
    --ignore fieldmaps \
    --participant-label $subj \
    --md-only-boilerplate \
    --fs-license-file $FS_LICENSE \
    --nthreads $nthreads \
    --stop-on-first-crash \
    --work-dir $SCRATCH/Work

Version:

24.1.0

Environment (Docker, Singularity / Apptainer, custom installation):

Singularity

Data formatted according to a validatable standard? Please provide the output of the validator:

PASTE VALIDATOR OUTPUT HERE

Data went through bids-validator and no error.

Relevant log outputs (up to 20 lines):

PASTE LOG OUTPUT HERE

The log looks fine, no error presented.

Screenshots / relevant information:




Hi @meishai can you try 25.0.0, and confirm that you do not get artifacts without any SDC? You can also consider SynBOLD-DisCo to create a synthetic fmap input.

Best,
Steven

Thanks Steven! A quick response - I actually ran the fmriprep without any SDC before this batch, just for comparison. And I did not observe any distortion caused by pipeline without SDC.
I will take a look into SynBOLD-DisCo as an alternative, thanks!