Dear Monty,
It isn't clear to me what you are trying to do.
VBM looks at changes in geometry (morphometry) and requires good quality images where segmentation and non-linear registration can be run. It is unlikely that your diffusion images are of that quality or contain the right information. We would recommend using TBSS instead to look at voxelwise changes (restricted to the centre of the major tracts, as these are the locations where reliable correspondences between subjects can be established).
All the best,
Mark
On 24 Jun 2014, at 15:36, Monty Waite <[log in to unmask]> wrote:
> Dear all
> I am trying to run a higher level analysis on DWI data acquired in 18 subjects on 2 factors at two levels. I am interested in voxel level changes in GM ADC
>
> I have registered all the single volume ADC maps to standard space
>
> Then I've concatenated them (according to my design matrix order) using fslmerge
>
> Am now trying to run randomise using a ANOVA: 2 factors/2 levels Glm design
>
> Getting this error message:
>
> ERROR: Program failed
>
> An exception has been thrown
> Logic error:- detected by Newmat: index error: requested indices = 1, 91408
>
> MatrixType = Rect #Rows = 72; Cols = 91407
>
> Am basically wanting to try a VBM approach with my DWI ADC maps - is that possible?
>
> Thanks!
>
> Monty
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