Dear Dayana,

The option to apply distortion correction was already present in previous versions as part of realignment step (in particular the preprocessing step called 'realignment & unwarp & distortion-correction') but in order to be able to use this step users needed to first go to SPM's fieldmap toolbox and manually create there a series of vdm files (voxel-displacement maps), one per subject, from their corresponding fieldmap acquisition magnitude&phase files. This was a time consuming and somewhat complicated process, so in the latest release we simply added the ability to have CONN create these vdm files directly for you from your scanner fieldmap acquisition files (this is the new preprocessing step called 'functional_vdm_create').
In order to use this new vdm-create step you simply need to:

1) define a new secondary dataset in Setup.Functionals and name/label it 'fmap'

2) enter there two files for each subject (or two files per session, if you have obtained different fieldmaps per session), the first should be the magnitude scan, and the second the phase-difference scan. You may combine those two files as a single 4d file before importing them, or you may simply select the two files when importing them in CONN's gui, whatever you find simpler. The imported files should look something like in the attached example image

and 3) running the functional_vdm_create step will create the corresponding vdm files for you, and place them in a new secondary dataset (named 'vdm') where they will be read from when you run the realignment & unwarp & distortion-correction step

Hope this helps
Alfonso


Originally posted by Dayana Hayek: