Dear FreeSurfer experts,

 

After running the longitudinal pipeline with QDEC, I needed beta-values of the associations between my main continuous variable and the significant cortical cluster, as well as of all the nuisance factors/categorical variables. Since the summary file doesn’t list beta values, I attempted running this command to find beta coefficients:

 

mri_segstats --i beta.mgh --annot fsaverage lh lh-Avg-long.thickness-spc-Parietal_WMH-Cor/mc-z.abs.th20.sig.ocn.annot --excludeid 0 --avgwf avgwf.dat

 

From this, I got this output file listing beta values for 1 cluster (entorhinal cortex) that was related to my main continuous IV (parietal WMH). I’m struggling to understand how to still compute 1 beta-coefficient per variable from this list. I understand that this list, based on my fsgd file, can be split into 4 sets of numbers, but I’m not sure what do next.

avgwf.dat:

    0.93879

   -8.80748

    0.38452

    3.13252

   -0.09493

   -0.13107

   -0.09960

   -0.31087

   -0.02291

    0.03127

   -0.02417

   -0.07858

    0.13087

    1.80749

    0.32535

    0.64947

 

Below is how my fsgd file was structured:

 

GroupDescriptorFile 1

Title ParietalWMH_age_gender_APOe_EC_left

MeasurementName long.thickness-spc

Class APOE_statusNO-genderF

Class APOE_statusYES-genderF

Class APOE_statusNO-genderM

Class APOE_statusYES-genderM

Variables Parietal_WMH age_years Avg_ECthickness

Input W38284_base APOE_statusNO-genderF 0.732010 85.830000 3.125000

.. (only listing the 1^st Input line here)

 

My contrast file (C.dat) looks like below:

0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0

 

So basically, I would like to get beta coefficients for the below variables:

• Parietal WMH
• Age
• Gender
• APOE status
• Average EC thickness (baseline values)

 

Thank you so much in advance for your help!

Batool