I have used SPM realign to perform a realignment of a later image to an earlier image. I would now
like to perform an inverse realignment of a tracing performed on the earlier image (and converted to
analyze format) into the space of the later image. I was wondering how to manipulate the .mat file to
get the inverse realignment? I realize that I could just run realign again in the opposite direction,
transfer the .mat data to the traced image using spm_vol and spm_write_vol, then perform
spm_reslice, but figured there might be a less computationally intensive/time-saving way to
calculate the .mat data than running spm_realign again in reverse. Thanks for any help you may
have to offer.