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Dear SPM experts, I have conducted VBM analyses in SPM8 both with and without the use of a mask. The issue I am facing is that I am encountering blobs outside the brain (see figure 1 for results without a mask and figure 2 for results with a mask). While I understand from previous posts on the mailing list and Ridgway et al.'s 2012 paper that this is a common issue, I do not understand why this is still occurring when I apply a mask. From my understanding the mask should limit the search space to that area specified and no results should occur outside the mask area. The images were processed using the DARTEL protocol and the mask was normalized to the SPM T1 template. I have checked the mask by overlaying it onto the T1 template and it appears to fit perfectly. Has anyone else experienced issues with blobs outside the brain when a mask was applied? If so how did you deal with it? I would very much appreciate any help, suggestions or explanations. Sincerely, Moyra Mortby Dr des. Moyra Mortby Postdoctoral Research Fellow CENTRE for RESEARCH on AGEING, HEALTH and WELLBEING ANU College of Medicine, Biology & Environment Building 63, Eggleston Road THE AUSTRALIAN NATIONAL UNIVERSITY ACT 0200 Australia T +61 2 6125 8413 | F +61 2 6125 0733 [log in to unmask] <mailto:[log in to unmask]> http://crahw.anu.edu.au <http://cmhr.anu.edu.au/>