Dear Rosalia

In my opinion, the AD values are OK and are not constant. The RD values are clearly wrong (they should be similar to AD values in magnitude).

The RD value you report (155323) might be the volume of the skeleton.

HTH

Cheers

Jürgen

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Am 28.12.2015 um 08:01 schrieb Rosalia Dacosta Aguayo:

Dear FSL experts,

I have been doing calculations in order to get the average of FA, AD, and RD values for all my subjects in order to adjust for those variables as possible confounders in my results (part of my sample has lesions that may affect WM structure). Well, whereas FA shows some variability, AD and RD values remain constants....(see the three columns...). I have two questions regarding this.

1. The first one is it is normal to get similar AD values for all the subjects as well as similar RD values.

2. Does it make any sesnse to try to covariate for AD and RD values taking into account they remain constant?? I ask this question because I am interested in studying FA, RD and AD maps....

Thank you for all your help.

Rosalia.

FA_VALUES	AD_VALUES	RD_VALUES
0.394522	0.001156	155323
0.408431	0.001103	155323
0.407739	0.001121	155323
0.362224	0.001173	155323
0.405417	0.001079	155323
0.401938	0.001157	155323
0.407141	0.001145	155323
0.341876	0.001218	155323
0.36687	0.00116	155323
0.378267	0.001149	155323
0.383875	0.00116	155323
0.368302	0.001179	155323
0.402161	0.00114	155323
0.335709	0.001207	155323
0.37291	0.001164	155323
0.391186	0.001186	155323
0.335775	0.001249	155323
0.317808	0.00119	155323
0.389519	0.001155	155323
0.246906	0.001528	155323
0.376403	0.001117	155323
0.373154	0.001167	155323
0.345241	0.001159	155323
0.384342	0.001178	155323