Hi MRtrix experts,

As a relatively new user of MRtrix I’m currently trying to sample MD and FA values from a tck file, but I’m not sure about how to do this correctly. For sampling FA values I used the following commands:

```
dwi2tensor dwi_preproc.mif tensor.mif
tensor2metric tensor.mif -fa fa.mif
tcksample -stat_tck mean trackfile.tck fa.mif output.file
```

Then, I calculated the mean of the output values in Excel. From what I’ve seen in other topics, I am pretty confident that this is the right way to go. However, I doubt whether this approach is also the way to go for sampling MD values. I did not come across many examples in other topics. If it is the right way to go, would it look like this?

```
tensor2metric tensor.mif -adc adc.mif
tcksample -stat_tck mean trackfile.tck adc.mif output.file
```

Is using the `-stat_tck mean`

option the right way to go for sampling MD values? It feels a bit odd to use a mean option on a mean parameter…

Any suggestions are welcome and thanks a lot in advance!

Best, Rianne