Setting acquisition parameters for DWI Preprocessing and CSD

Hi MRTrix experts,

I have some DWI studies acquired with a b value of 1500 s/mm2 and 32 directions (because our license does not allow a greater number of directions unless you acquire 32 directions twice to get 64).

Is a b value=1500 and 32 directions enough to do the preprocessing, the Constrained Spherical Deconvolution and get good results?

Thanks a lot and best regards,


Hi José,

Similar questions have been asked a few times in the past (see e.g. this post or this post). Basically, CSD is certainly feasible and will run, but the quality of results may be questionable. It depends to a large extent on the SNR, and also what you plan to do with the results exactly. Assuming sufficient SNR, I’d expect you would get decent results here, though you could obviously get better with a slightly higher b-value and more directions, and even simply repeating the acquisition to boost SNR will already achieve a lot (32 directions is enough for a decent lmax=6 fit) – just make sure you don’t average the images if you do that.

Hope this helps,

Thanks you very much for the information