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The b0 count as one of the 3 b-vals. I’m using a similar DWI protocol as yours and it’s working great. De : Andreas Bartsch<mailto:[log in to unmask]> Envoyé le :1 octobre 2016 16:13 À : [log in to unmask]<mailto:[log in to unmask]> Objet :Re: [FSL] Multi b-value DTI Hi, don¹t they suggest to use 3 bvals or are the b0-scans along with b=1k + 2k sufficient for this? Cheers, Andreas Am 29.09.16, 17:54 schrieb "FSL - FMRIB's Software Library on behalf of Cabana Jean-François" unter <[log in to unmask] on behalf of [log in to unmask]>: >I would suggest having a look at this : > >https://github.com/NYU-DiffusionMRI/Diffusion-Kurtosis-Imaging > >to fit the DKI tensor. You¹ll also get your usual DTI parameters, but >they should be more accurate as the fitting will account for the kurtosis >present at b=2000. > > > >De : Saad Jbabdi<mailto:[log in to unmask]> >Envoyé le :29 septembre 2016 11:47 >À : [log in to unmask]<mailto:[log in to unmask]> >Objet :Re: [FSL] Multi b-value DTI > >Hi - with b=1k and b=2k, you should have significant kurtosis, and >therefore you will get different-looking tensors (different MD but also >FA), though these will be shifted and highly correlated. Fitting a single >tensor to both data will give something in between and the data fitting >won¹t be that good in most of the brain tissue. > >Cheers, >Saad. > > > > >On 29 Sep 2016, at 16:17, Patrick <[log in to unmask]<mailto:[log in to unmask]>> >wrote: > >Hi experts > >I've searched around the forum a bit but seem to be getting slightly >differing answers to my question. > >I'm collecting multi b-value diffusion data (using a NODDI sequence). I >have the matlab toolbox to reconstruct NODDI specific parameters (ODI, >NDI etc) but I was wondering about the accuracy of using FSL to >reconstruct my FA and MD maps. > >The sequence I use is a 2 shell sequence with 36 directions at b=1000 (+4 >b0) and 72 directions at b=2000 (+4 b0). The two shells are collected >interleaved and the data is processed in a single 4d data file. > >The resulting MD and FA maps look great but I want to ensure that FSL is >reconstructing these maps accurately before proceeding with my >quantitative data analysis. > >Thanks >Patrick McCunn