Hi Benxamín - Those can occasionally arise due to noise. You're more likely to
see them if you're looking at single voxel values than average values over
multiple voxels. That sequence of values in the .9-1 range does look quite high
though. Another possibility would be miscalculation due to incorrect b-values.
a.y
________________________________
From: freesurfer-boun...@nmr.mgh.harvard.edu
<freesurfer-boun...@nmr.mgh.harvard.edu> on behalf of Benxamin varela lópez
<benxa...@gmail.com>
Sent: Wednesday, December 18, 2019 1:06:38 PM
To: freesurfer@nmr.mgh.harvard.edu <freesurfer@nmr.mgh.harvard.edu>
Subject: [Freesurfer] FA index greater than 1
External Email - Use Caution
Dear freesurfer experts
I am a beginner in DWI data processing and my question may be absurd, if so, I
apologize in advance.
I am using TRACULA for the analysis of my DWI data. Reviewing the outputs of
the statistics for the FA index I realized that some of these are greater than
1. Considering that FA oscillates between the values 0-1, how is this possible?
I send to you in attached the .txt with the average FA values for the Forceps
Minor where the "anomalous" values can be observed.
Thanks in advance
Best regards
Benxamín
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