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See below. On Mon, Nov 25, 2013 at 5:33 AM, Naoki Hirabayashi < [log in to unmask]> wrote: > Dear Experts, > > I'd like to know if I should exclude image with even a little motion > artifact in VBM analysis. > > In a paper they exclude images with excessive motion of > 3mm. > > How can I measure distance of motion? > This is the amount of movement needed to make the image line up together. This is computed during motion correction. > > How much motion artifact should I exclude? > There isn't a definitive value. If you have more than 1 voxel of movement over a run, I'd discard that run. If you have more than .75mm translation or 1.5 degree of rotation between adjacent time points, then I'd exclude those time points. > > Any suggestion would be highly appreciated. > > > Thank you so much, > Naoki Hirabayashi >