I know that there is no ground truth for
fod2fixel, however, I’d be glad to know your opinion on which value is optimal for my data.
The data I’m working on has b=0,700,1000,2000 in 64 directions. I did
dwi2response dhollander and
ss3t_csd_beta1 on b=0,2000.
Here are different
fmls_peak_value index.mif files overlaid on the wmfod_template.mif:
for 0.10 (default):
for 0.06 (suggested by MRtrix’s FBA guideline):
The lower the value, the more “bleeding” is observed into the non-white matter tissue (such as basal ganglia or maybe CSF). The higher it is, you will lose fixel data in cross-fiber regions (even with fmls_peak_value = 0.1).
My intuition was to go with the middle value, 0.08, however, I don’t know if that “bleeding” by choosing the suggested 0.06 value may be problematic in the next steps.
p.s. another option is to go with a “multi-verse” kind of analysis, and reporting all cut-off values, which computationaly may not be really what I’m looking for.