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... and with 6 directions it will certainly not work! T On 7 Mar 2007, at 23:15, Andreas Bartsch wrote: > Hi, > the minimum that we would advice are ~ 30 diffusion gradients. See > previous posts on this. > Hope this helps. > Best regards- > Andreas > > Dr. A. Bartsch > Dep. of Neuroradiology > Univ. of Wuerzburg > > ________________________________ > > Von: FSL - FMRIB's Software Library im Auftrag von Igor O. Korolev > Gesendet: Do 08.03.2007 00:07 > An: [log in to unmask] > Betreff: [FSL] Fiber Tracking in FDT using DTI data with 6 directions > > > Dear Dr. Behrens, > > > Thank you for your rapid response regarding the FDT tutorial data. > Now, I would like to ask about the FDT analysis of our team's data. > > > Specifically, our DTI data was acquired in only 6 directions > (diffusion-weighted acquisitions) plus 1 B_zero, non-diffusion- > weighted acquisition. > Given that it takes a minimum of 6 DTI acquisitions / gradient > directions to compute a tensor, is it still statistically valid to > use FDT / Probabilistic Tractography > to conduct fiber-tracking analysis of our data? That is, will we > have enough acquired DTI data to reliably estimate the probability > density function used for determining the > connectivity distributions? (it seems that NO). Or is it only valid > to use FDT for conducting tractography in DTI data acquired in more > than 6 directions? > > > Thank you for your help. > > > -Igor Korolev > > > > -- > ------------------------------------------------- > Igor O. Korolev > D.O./Ph.D. Program > College of Osteopathic Medicine > Neuroscience Program > Michigan State University > Email: [log in to unmask]