Good b-value sensitivity parameter for 2shell

[lrq3000]

Thank you very much! I discussed with our Siemens healthineer and we unfortunately don’t have the required the access to these advanced parameters, but we might in the future after someone in my team do the required training.

So I tried to tweak to get 3-shells, but unfortunately multiband x4 was too noisy, so I reduced to x3, and I settled for b1000 + b2000 (instead of b1000 + b3000) as b3000 was noticeably too noisy on our machine, for a total of 11:45min. Here is the result (single-shell vs multi-shell analysis for the same healthy subject):

I don’t have much experience with multi-shell, but I think it looks fine, right?

I also looked at the possibility to acquire multiple sequences and concatenate as one multishell sequence prior to analysis, but I found a thread that suggest this would then require a normalization and is thus disadvised:

Multi tissue CSD and pooled b0s across shells

Dear MRtrix team, Can I check if the multi-tissue CSD pools the b=0 volumes together to estimate the b=0 signal? I am told that in some scanners the b=0 is different for different shells and to correct for this issue, one needs to first compute the normalised signals (e.g. b=700 signal divided by b=0 signal) for each shell separately. Is this issue likely to affect connectome construction and if so how? Thanks so much for your help. Peter

So for the moment I think we will settle with this setting, which seems quite good and way better than what we had before Thank you very much!