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Hi - to check the Z component you need to look somewhere where there *is* a Z component - so *not* the corpus callosum! Check in (eg) the corticospinal tract and you will probably see that one of the two options is clearly wrong. Cheers. On 31 Jul 2014, at 07:53, Cornelia McCormick <[log in to unmask]> wrote: > Hello experts, > > I am worried that the directions of the bvecs I use are not correct > and I would like to know how you would go about checking them. I have > two versions (1. from the scanner, and 2. MRICRON created by their dcm > import function). The values in these files are the same, just that > the z-dimension in the MRICRON created ones are mutliplied by -1. > I used topup, eddy and dtifit with both bvec files to produce the > first vector to look at obvious landmarks such as the corpus callosum. > The orientations look pretty good and pretty much identical between > files. So, does it matter whether the z-direction is flipped? Or is > there a way of telling the right bvecs from the wrong ones? > > Thanks very much for your help, > Conny --------------------------------------------------------------------------- Stephen M. Smith, Professor of Biomedical Engineering Associate Director, Oxford University FMRIB Centre FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK +44 (0) 1865 222726 (fax 222717) [log in to unmask] http://www.fmrib.ox.ac.uk/~steve --------------------------------------------------------------------------- Stop the cultural destruction of Tibet