Hi,
The rp_*.txt files represent the motion parameters relative to the first
image of each run, so that the parameters for the first image of each run is
zero (or near, due to rounding issues I assume). Thus, there is no
information on how much the first image of each run moved relative to the
reference image. However, when SPM presents the motion parmeter plot in the
graphics window following realigning, it shows all the shifts relative to
the very first image (or whatever was the first image selected during
realign). Is there a way to recover this information (i.e., the shift of the
first image of each run relative to the reference image) post-hoc without
modifying spm_realign?
(all this refers to SPM2 - not sure if the above has been modified in newer
SPM versions)
Thanks,
Leon
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