[Freesurfer] Questions about byvoxel statistics from Tracula

Hello

I'm using Tracula to analyse our DWI-images. Freesurfer reconstructions of the corresponding T1-images have been perfomed before. Respectively, the version used are 1.53 and 5.3. The Tracula process works fine and I have extracted the statistics for all tracts. About this statistics, I wanted to know what is the difference between FA and FA_Avg ?

An other question about the values extracted is about the coordinates in the file "byvoxel.txt". Are they correspind with the coordinates of the voxel in the dtifit image were the values were extracted?

The last question, can we extracted the same by tract statistics from an other image like a PET registered to the DWI with your code?

Thanks for your answer