Dear freesurfer experts,
I started using qdec for comparing cortical measures in adolescent patients
with ADHD versus typically developing adolescents and I have a few questions
concerning the ROI analysis as well as the Desikan-Killiany versus Destrieux
English is not my native language so please excuse typing errors or wrong
1) Is it somehow possible to have the significant clusters mapped onto the
Destrieux atlas in qdec instead of the Desikan-Killiany one?
2) I would like to export the mean thickness/surface area from significant
clusters to SPSS to correlate them with clinical symptoms. I understand you can
either use means from the stats tables (aparc_thikness_lh.txt etc.) or manually
draw a ROI and then map the lable back to other subjects. But is there also a
way to simply export the measures from the significant clusters that show up
without drawing around them or export measures from the peak vertices?
3) If I use methods as described in 2), do I have to be concerned about
‘double dipping’ or ‘circular analysis’?
4) Does the measure ‘area.pial’ you can select during design creation
correspond to ‘cortical surface area’ and the measure ‘area’ to ‘WM surface
area’? Which measure do the aparc_area_lh.txt files that I get when generating
stats data tables correspond to? I do not see aparc_area.pial.txt files, should
I be getting them?
5) After reading a lot about correcting for global brain measures I am
still confused about the best way to do it. I am quite sure that for the
volume-based measures it is best to control for ICV/eTIV but for thickness and
surface area I read different approaches from not controling to using total
brain volume, global thickness or ICV. Is it safe not to control for anything
for thickness measures as I do not expect any kind of atrophy in my sample?
What should my decision be based on?
Sorry, these are many questions – I appreciate any thoughts on these problems,
thank you so much!
Lea Backhausen, B.Sc.
Department of Child and Adolescent Psychiatry, Faculty of Medicine of the
Technische Universität Dresden, Dresden, Germany
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