Hi Dan
the aseg volumes are native, *not* ICV-corrected. And yes, the standard way to account for ICV is to include it as a covariate
cheers Bruce On Thu, 18 Jul 2013, Daniel LaFreniere wrote:
Dear FS Experts, I had a question concerning volumetric analysis. I will soon be starting this analysis and have exported my data into a text file using the flag:
asegstats2table --subjects [list_of_subjects_for_analysis] --meas volume --tablefile asegstats.txt
All of my subjects have the entire recon-all pipeline completed but nothing else. I'll be running my stats with SPSS but was wondering about intracranial volume (ICV aka eTIV). I read through the relevant info section on the FS wiki and it states that "correction [for the volume of the cranium] is performed because certain structures scale with head size...". However, I didn't see anywhere on the page stating if the correction for ICV (eTIV) is carried out automatically during the FS pipeline.
Therefore, I'm wondering if ICV is accounted for when volumes are calculated within the aseg.stats file during autorecon3 (through mri_segstats and mri_label_volume). If not, do I have to do anything else to the data to ensure accurate analysis? I.e.: Should I account for ICV as a covariate during normal stats analysis or can I just run my analysis as I normally would and leave ICV out of the covariates?
Thank you very much for your help,
Dan