thanks for your kind words. And yes, I’d solve question 2 exactly as you would – since the resolution of the VTAs is so good a reslice to the anchor preop image (often the T1) won’t harm them and we never felt the need to export one in that resolution.
Re q 1, two options:
1. In Lead Group create a new variable with one entry for each patient (the default) and fill it with ones (e.g. put a 1 into each row). Then check “Map regressor to VATs”, select all patients and click visualize 3D. This will create a nifti file (in the lead group directory) that is the group’s VTA. It will also visualize the group VTA in the 3D viewer directly.
2. Second option is to just create it with e.g. SPM imcalc or fslmaths. In SPM imcalc, select a template (e.g. MNI space) first and then all VTAs. Then only use i2, i3, i4.. (ignore i1, i.e. the template) in your expression. The result will still be exported in MNI space (i.e. in the same resolution of i1, the template you selected).
If you have the joint VTA as a nifti file (which will result from either solution 1 or 2) then you can always display that (or any other nifti file) in the lead DBS 3D viewer by choosing Add Objects -> Add Roi.
Hope this helps!