Dear Jasper,

Yes, you are right, the error comes from fslmerge. I checked image dimensions for the images I want to merge in order to run topup. B0 has dim1 74 dim2 72 dim3 48 whereas B0flipped has dim1 72 dim2 74 dim3 48. 
Can I still use these images to run eddy? Is this a problem that the diffusion volumes are acquired in anterior-posterior phase encoding and B0flipped is acquired in right-left phase encoding direction? 

Thank you,
Monika



2014-09-26 21:41 GMT+08:00 Jesper Andersson <[log in to unmask]>:
Dear Monika,

>
> I want to use eddy distortion correction of dsi data. We acquired diffusion volumes in A>P  phase encoding direction and an additional B0  in R>L. I tried to run Topup on the B0 volumes but got an error message saying "error in size-match along non-concatenated dimension".

That doesn’t sound like an error message I recognise from topup. Are you sure that doesn’t come from fslmerge (for example if you have a script that prepares the data for you that calls fslmerge)?

Jesper


>
> Any help on this will be greatly appreciated.
>
> Thank you,
> Monika