When I look at the BrainSegVol and BrainSegVolNotVent in wmparc.stats, the values are around 200,000 - 300,000. However, when I look at the same measures in aseg.stats, the values are around 1.1L - 1.5L. When I sum up the individual ROIs in wmparc, it comes out to >1L. I am currently using freesurfer 4.3.1. When I look at the aseg.stats files from freesurfer 3.0.5, ran on the same subjects, the values are up around that 1 - 1.5L range. This is consistent across all of our subjects: > 100 and from two different scanners at two locations.
# Measure BrainMask, BrainMaskNVox, Number of Brain Mask Voxels, 1774481, unitless
# Measure BrainMask, BrainMaskVol, Brain Mask Volume, 1774481.000000, mm^3
# Measure BrainSegNotVent, BrainSegVolNotVent, Brain Segmentation Volume Without Ventricles, 243312.000000, mm^3
# Measure BrainSeg, BrainSegNVox, Number of Brain Segmentation Voxels, 275688, unitless
# Measure BrainSeg, BrainSegVol, Brain Segmentation Volume, 275688.000000, mm^3
# Measure IntraCranialVol, ICV, Intracranial Volume, 1302696.178406, mm^3
My question is why would wmparc so severely underestimate the BrainSegVol measure? If I can not fix it, should I take the BrainSegVol from the aseg.stats file?