Hi list, I obtained cortical thickness and volumetric results before and after correcting them for defects.
I just did some wm edits and mostly controls points in the top of the head (some subjects had less signal so I put control points in order to allow for a good surface reconstructions).
When comparing the values:
EXPECTED - Same volume values for subcortical structures, i.e.: same thalamic volume before and after - Different CT values in the edited areas and only for the edited subjects, i.e.: lh_paracentral_thickness - Different volumetric values only for the edited subjects in, for example: lhCortexVol, CortexVol, CorticalWhiteMatterVol
NOT EXPECTED - Same values for EstimatedTotalIntraCranialVol.
I was controlling thalamic values with the eTIV, (using Raz 2005's formula)*, but before and after correcting almost half of the subjects, obviously, I obtain the same results.
- Should I use a different value other than the eTIV? - Is normal that the eTIV doesn't change but the rest of the values are changing? The brain is definitely different after the control points, it grows a little bit upwards.
any information on this will be appreciated! thanks, Gari
PS: * Volume (adj) = Vol(rawi)-b*(ICV(i)-mean ICV), where b is the slope of regression of an ROI volume on ICV