Fixel-based analyses of laterality

Hello, MRtrix experts

I was doing a FBA of laterality following the pipeline in this paper : Helena Verhelst, Thijs Dhollander, Robin Gerrits, Guy Vingerhoets,Fibre-specific laterality of white matter in left and right language dominant people,NeuroImage (2021)

But I got stuck by several questions.

  1. How to make a single hemisphere fixel mask. I used to make masks based on atlas, but I had no idea how to produce a mask in fixel format based on the study-specific template. And in the paper, they referred that "restrict the fixel analysis mask to only contain fixels for which correspondence [fixel mask and those of individual subjects] with at least 90% of all participant hemisphere data could be established. I wondered how to accomplish this step and combined with hemisphere mask .

  2. In order to calculate log-ratio of laterality index [log(FDoriginal/FDfliped)], in this paper they set the FD to a non-zero low value of 0.01 instead (this equals 1% of one calibrated unit of FD) . I did this using command [ mrcalc fd.mif 0.01 -add fadadd.mif ] for each subject’s fd file, but I don’t know this step should be done before or after fd smooth.

  3. fixelcfestats seems not include One-sample T test. Are there other ways I can do this?

Thank you very much !


Kitty Zhu