voxel resolution


I have a dataset in which one participant has a different voxel resolution than the other participants, which has led to an issue in analyses (I can run my ANOVA script if I remove that participant since the rest have the same voxel resolution).

The one participant has dataset dimensions of nx = 161 ny = 191 nz = 141 nxyz = 4335891
The other participants have the dataset dimensions of nx = 161 ny = 191 nz =151

Do I have to pre-process that one participants again? If so, how can I force the voxel resolution to be the same as the others?

Thank you,

Those numbers aren’t exactly the “resolution”; they describe the grid size. It looks like you have more slices in the z-direction for one subject’s dataset than the others, but the voxel size may be the same. Using a command like

3dinfo -d3 mydset.nii.gz

will give you the dimensions of a voxel. If you are using afni_proc.py and transforming your data to a standard space like MNI or TLRC, the template dataset will define your grid space, and you can use the option “-volreg_warp_dxyz” to define the voxel size of the output. If your datasets have the same voxel size to start, the same dxyz voxel size will be set for the output even without the option. See the help for afni_proc.py for more help on this.