# Understanding FiberTractMeasurements output

**URL:** <https://discourse.slicer.org/t/understanding-fibertractmeasurements-output/37284>\
**Category:** SlicerDMRI\
**Created:** [July 9, 2024, 2:03pm UTC](https://discourse.slicer.org/t/understanding-fibertractmeasurements-output/37284 "2024-07-09T14:03:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Calth822](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/calth822/32/77248_2.png) [@Calth822](https://discourse.slicer.org/u/Calth822)\
**Post date:** [July 9, 2024, 2:03pm UTC](https://discourse.slicer.org/t/understanding-fibertractmeasurements-output/37284/1 "2024-07-09T14:03:40Z")

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Hello, I following the WMA tutorial and I have understood all steps except for the last step of tutorial, " 8. Fiber tract diffusion measurements".

I have been able to follow the tutorial and extract the diffusion measurements to the CSV file as per the tutorial (see image)

 ![Screenshot 2024-07-08 194405](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/d/3/d352545b3c9b18810b31d0b7f40747f684825b40.png)

However I do not understand some of the columns present in the file and I have not found any documentation to specify what they mean.

I understand the following columns:

- Num\_points
- Num\_Fibers
- Mean\_Length
- HemisphereLocation
- cluster\_idx

But I am unsure of the following and why there are two of the same for some measurements when I assumed there should only be one:

- FA1
- FA2
- Trace1
- Trace2

Any help in understanding these columns would be greatly appreciated

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<div class="post-metadata">

**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [July 9, 2024, 3:14pm UTC](https://discourse.slicer.org/t/understanding-fibertractmeasurements-output/37284/2 "2024-07-09T15:14:37Z")

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There are two FA and Trace values because the pipeline uses the 2-tensor option of [UKF Tractography](https://github.com/pnlbwh/ukftractography).