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Hello- Short question: Is there any clear evidence that using a fiducial marker that shows up on the T2* is not a wise idea? Long winded version: We often use a fiducial marker to ensure we never left-right flip an image. I recently used a marker that shows up in the EPI T2* scans as well as in the T1 anatomical scans. Image preprocessing appears to proceed smoothly - the realignment and normalization look very sharp. However, I notice that the EPI unwarping image that SPM2 generates clearly includes the marker in its map. This sounds potentially bad, as the marker will not move when the head moves. I am including a image of the original EPI image, the undistortion map generated by SPM and the undistroted image: http://www.psychology.nottingham.ac.uk/staff/cr1/unwarp.gif I masked the fiducial in a single individuals scan and there was no difference in statistical results (my measure was how many voxels survived FWE corrected analysis, resulting 1600 when the fiducial was included and 1603 when it was masked). Based on this, I am tempted to continue using this fiducial marker. However, I recognise that most of people I have tested so far have kept their heads very still, and I am wondering if I should be concerned when I test people who move their heads a bit more. -chris