I was wondering how the calculations of the wm volume were performed as well. The six values below are volume values from aseg I believe. I assume mris_wm_volume does more than sub-divide these regions into the wm parcellations, but probably also includes partial volume estimations along the wm/gm surface, is this correct? I basically have the same question for the gm volume values in aparc.stats; do they include partial volume calculations from the gm/pial and gm/white borders? Which binary is used to create these values for gm in aparc.stats... is it mri_segstats (with --pv)? I was assuming it would be an mris (surface) calculation as well. I am asking because if you use tkmedit to view the ?h.surface files and load the aparc+aseg or wmparc segmentation volumes in also, the surfaces and the segmentations don't seem to line up. Is there a way to create a segmentation volume that includes partial-volumed voxels at the gray/white and gray/pial boundries? Thanks for your help.
Chris Bell
the interior voxels are only included in the volume if they are one of the following in the aseg.mgz:
case Left_Cerebral_Cortex: case Right_Cerebral_Cortex: case Left_Cerebral_White_Matter: case Right_Cerebral_White_Matter: case Left_WM_hypointensities: case Right_WM_hypointensities:
cheers, Bruce
On Tue, 15 Jul 2008, Marin Richardson wrote:
OK, so aparc.stats is better for cortical gray matter. I want to look at the parcellated white matter volumes as well - is the only/best option to use the wm volumes from wmparc.stats?
Also, when using mris_wm_volume to calculate total white matter, I saw the result defined as the volume within the white matter surface minus non-WM structures? Can you tell me which regions are and are not included?
Marin
Doug Greve <[EMAIL PROTECTED]> 7/15/2008 12:02 PM >>>
It is better to use the aparc as it is derived from surface measurements, which have sub-voxel resolution. The wmparc.stats are generated by counting 1mm^3 voxels.
doug
Marin Richardson wrote:
Hi all,
I noticed that the gray volumes for parcellated cortical regions in wmparc.stats are different from those for the same region in aparc.stats (e.g. ctx-lh-middletemporal = 8419 in wmparc.stats, middletemporal = 9466 in lh.aparc.stats). Why are the values different and which one is a better measure to use?
Thanks, Marin