Repositioning Structural MRIs to MNI space
Define the anterior commissure as the origin
Reorient images with anterior commissure as origin
After the AC is defined, it's coordinates relative to the existing origin are found in the "Crosshair Position" box, defined in mm, for the x,y,z axes. For the the structural below this corresponds to [0.0 38.5 16.1]. [ ]. Since we want to make the AC the origin, the image needs to be "shifted" by these values. Hence in the "right {mm}" box[ ] the value [0.0] is entered, in the "forward {mm}" the value -38.5, and in the "up {mm}" box the value -16.1 [ ].
NOTE that the sign of the values entered have the opposite sing than the one in the coordinates box. This is of course because the values in the coordinates box represent the differences between the