fMRI Pre-Processing

fMRI Anatomy Processing Structure

fMRI Anatomy Pre-Processing Diagram

Alt text:

Flowchart titled “FMRI Anatomy Processing Structure.” A blue box labeled “Create 3D image (dcm2nii)” branches to two modules: “Homogeneity correction (in-house code)” and “Skull stripping (FSL).”

On the right, text reads “Module selection and ordering is user-selectable,” with arrows indicating that processing steps can be arranged by the user.

Anatomy File Structure

Subdirectories for each structural series (e.g. "t1sag_208sl")

 t1sag_208sl.nii

3D structural image in "rawest" form, converted from scanner DICOM files.

ht1sag_208sl.nii

Image with in-house homogeneity correction applied.

eht1sag_208sl.nii

Skull-stripped image using FSL BET.

dicom.tgz

Compressed directory containing DICOM files for this series.

fMRI Functional Processing Structure

fMRI Functional Pre-Processing Diagram

Flowchart of an fMRI functional processing pipeline. The sequence begins with “k-space despiking (spiral acq only)” followed by “Create 4D image (EPI: dcm2nii, Spiral: matlab recon).” From there, branches lead to “Physio noise correction (RETROICOR),” “Slice-time correction (SPM),” and “Motion + field map correction (FSL topup + SPM).” Optional modules shown in green include “Physio noise correction (COMPCOR)” and “Motion correction (FSL mcflirt).” A legend indicates blue boxes are default steps and green boxes are other available modules. Text on the right notes that module selection and ordering are user-selectable.

Functional (run) File Structure

Subdirectories organized as '[TASK]/[run_##]/'

 run_##.nil

4D time series image in "rawest" form, converted from scanner DICOM files or raw Pfile. 
Note: For multiband data, we discard the first 12 volumes of the acquisition.

prun_##.nil

Physiological noise correction using RETROICOR, if physio data was obtained.

varBefore.nii varAfter.nii

Variance maps before and after RETROICOR.

regressors.mat

Regressor matrix from RETOROICOR

t[p]run_##.nii

Slice-time correction (SPM).

vdm5_fpm0000.hdr/.img

Voxel displacement map calculated and used for field map correction.

rp_t[p]run_##.nii

Calculated translation (mm) and rotation (rad) movement parameters per volume, using the 10th volume of first run of the task as the reference.

Order of the 6 columns = [x_translation y_translation z_translation x_rotation y_rotation z_rotation]

ut[p]run_##.nii

Combined field map + motion correction. Field map is calculated with FSL topup and applied within SPM's realign_unwarp module.

dicom.tgz

Compressed directory containing DICOM files for this series.

Functional (field map)

Field map data found by extracting func/fieldmaps/fm_[TASK]/dicom.tgz

 i*MRDC*

Field map DICOM files

my_fieldmap_resized.nii

Calculated field map (nifti format)

fpm.img/.hdr

Calculated field map (Analyze format, required for SPM processing)

my_fieldmap_mag.nii

Calculated field map magnitude using FSL topup

 

my_fieldmap_mag_brain.nii

Calculated field map magnitude skull-stripped with FSL bet

DTI

run_##.nii

fieldmap/fieldmap.nii