Hi everyone,
We have run FreeSurfer on roughly 60 subjects for a study, and are
noticing some strange discrepancies for intracranial volume in
aseg.stats for 8 of them. Here is a subset of what we see in one of the
"bad" aseg.stats files:
# Measure CorticalWhiteMatter, CorticalWhiteMatterVol, Total cortical
white matter volume, 559928.546875, mm^3
# Measure TotalGray, TotalGrayVol, Total gray matter volume,
769545.059854, mm^3
# Measure IntraCranialVol, ICV, Intracranial Volume, 1263234.600914, mm^3
Here, the total volume of WM plus GM is 1,329,473.606729 mm^3, which
exceeds the intracranial volume by 66,239.005815. This does not make
sense - how can the volume of brain matter exceed the volume of the
space that encompasses it?
Does FreeSurfer generate a mask of the estimated intracranial volume? We
would like to superimpose it over the T1 to see how accurate the
estimation is for these cases. Also, does the mask (if it exists)
include the cerebellum?
Thank you for your help,
Nikhil Chandra