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Hi Pat, I don't know about your system specifically, but in the MGH DTI package distributed by Siemens, the vectors are in magnet space, so you have to rotate them if you use an oblique acquisition. Also, they are in LPS, not RAS. Like I said, I don't know about your specific system. doug Pat Vee wrote: >Hi all, > >I was wondering if someone could tell me the orientation (i.e., A->P, R->L, >I->S - or something different) that dtifit expects the bvecs file to be in. > I've been getting disappointing results using probtrack, where my tracks >terminate very quickly (though my FA and V1 maps look reasonable) - I've >been using the 35-dir ICBM sequence on a Siemens Trio (and the vectors >provided by >Siemens). However, I've become confused since I don't know if the vectors >should be in patient space or scanner space (and maybe these should be the >same...). If I sign flip my z vectors, the results look great - but I'd >like to be able to check to see if there's some way to verify that this is >the correct orientation of the vectors... > >Thanks, >Pat > > > > -- Douglas N. Greve, Ph.D. MGH-NMR Center [log in to unmask] Phone Number: 617-724-2358 Fax: 617-726-7422 In order to help us help you, please follow the steps in: surfer.nmr.mgh.harvard.edu/fswiki/BugReporting