exporting dSPM volumes?

I've attached a screenshot of our MNE toolbox operating on MEG data of
a visual evoked experiment. ?I need to analyse the locations of
"activation" outside of MNE, but I do not know how to do so. ?I would
like to dump a 3D volume of the dSPM map shown in the screenshot.
Ideally I'd like to dump a 4D volume (3D+time) of the dSPM map as the
time inside the ERP in the upper left window is incremented. ?How can
I do this? ?Thanks,
Erik