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Before any registration procedure in SPM, you usually need to have the images within about 20 degrees and about 3cm of accuracy before you begin (as there is no procedure for avoiding local optima). Spatial normalisation begins with an affine registration, which either gets a good solution or it doesn't. If it doesn't, then the effect should be pretty obvious. If it reaches a good solution for the affine part, then it shouldn't matter what the original starting estimates were as these shouldn't influence the nonlinear bit of the spatial normalisation. Best regards, -John > another raw image orientation question... > How important is it to orient T1-images in the AC-PC plane before starting > the preprocessing steps used in VBM. Has the origin of the image to be set > on the AC and how much are the linear and non-linear normalisation steps > influenced by that parameter ? > > Do I have to reslice my MPRAGE-data (0.4, 0.4, 1.5 mm) to other voxel > dimensions (e.g. 1, 1, 1 mm) before entering the preprocessing steps or is > that automatically performed by SPM? > > Any tip would be greatly appreciated,