External Email - Use Caution Hello FreeSurfer experts,
I have this interesting situation. I understand its important to include ICV as a covariate while conducting cortical volume (CV) analysis. So for my clinical sample (CL) vs healthy-controls (HCs): 1. If I do *network-wise* analysis (i.e., after parcellating the whole brain into 17 networks), I get highly significant differences in CV (MANCOVA: CL < HCs) for a specific network (say N1) - *if I include ICV as a covariate*, but not otherwise. 2. If I do *whole-brain vertex-wise* analysis, I get highly significant differences in CV (CL < HCs) for a specific cluster (which is overlapping with an area of N1) - *if I do not include ICV as a covariate*, but not otherwise. I am not sure how to interpret this i.e., ICV as a covariate for network-wise analysis plays an opposite role i.e., makes my findings stronger compared to ICV as a covariate for whole-brain vertex-wise analysis i.e., makes my findings weaker. Does ICV as a covariate add some kind of noise during whole-brain vertex-wise analysis? I would really appreciate any help in understanding this.
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