Are you sure that all your DTI images have the same acquisition parameters?!!
________________________________ From: freesurfer-bounces@nmr.mgh.harvard.edu [freesurfer-bounces@nmr.mgh.harvard.edu] on behalf of Elijah Mak [fkm24@medschl.cam.ac.uk] Sent: Thursday, March 24, 2016 7:33 PM To: Freesurfer support list Subject: [Freesurfer] FA and MD *positively* correlated within same regions ?
Hi Freesurfer Community,
I recently used mri_segstats to extract FA and MD as suggested here: http://freesurfer.net/fswiki/FsTutorial/Diffusion
Using the aparc+aseg and wmparc (resampled to diffusion space), I looked at some of the correlations between FA and MD in the same regions, and came across a few interesting ones.
wm_lh_entorhinal FA & wm_lh_entorhinal MD: r = 0.6, p <0.001 ctx_lh_entorhinal FA & ctx_lh_entorhinal MD: r = -0.3, p < 0.020
wm_lh_precuneus FA & wm_lh_precuneus MD: r = -0.6, p <0.001
As I understand, a clear-cut interpretation especially with regards to FA changes is not so easy! But could someone discuss / speculate as to why FA and MD could be positively correlated within the entorhinal WM region? That was found separately within a group of a elderly healthy controls and a group of dementia subjects.
Thank you for your time!
Best Wishes, Elijah