Sample size and power calculations

Has anyone had any experience with power calculations for studies using MRtrix, and specifically using “fixelcfestats” as a way of analysing the data?

I’m currently working with a statistician to see if we can do this and work out a sample size for a given effect size - and it’s proving a little more complex than expected.

Thought I’d throw the question here as I’m yet to find any reference to power calculations in any published manuscript when using MRTrix.