One other thing. I did the addition of all the structures in aseg and am a bit confused. Here are the numbers for one subject.
BrainSeg= 1035602 BrainSegNotVent= 1034954 These two are almost identical but that is most likely due to the lack of pv correction in BrainSeg, so I think that makes sense. When I sum all the structures in aseg I get 1027260 (which includes the five CC regions). This number is smaller than BrainSegNotVent, which doesn't make sense to me since I would expect it to be larger than BrainSegNotVent. Sorry for all the questions, I think FreeSurfer is great! Chris On Nov 3 2010, bell0...@umn.edu wrote: > > >I had a question about gray matter and white matter volumes in FreeSurfer >version 4.5. Sorry, we have too many subjects to rerun easily through 5.0. >There is no gray matter listed in aseg.stats in 4.5. The two options I see >are using mris_volume or summing the aparc gray matter structures, are >there pros/cons to this? More specifically, should the sum of the aparc gm >regions equal the surface-based gm volume from mris_volume or will they be >different? > The aseg.stats also produces surface-based wm volumes, which I presume need >the subcortical structures subtracted away, is there a command to do this >with mri_segstats or do I just need to run a loop for every subcortical >structure to get these corrected wm volumes? > >One last question. The mri_segstats says BrainSeg is computed WITHOUT >partial volume correction. My understanding was in the aseg pipeline every >voxel got assigned to a specific structure in aseg.mgz. So, I don't undestand how partial voluming comes into play? In BrainSeg are some voxels >counted twice as being part of two different structures, and then this is >fixed when the volume of each structure is reported in the aseg table? >Also, it would be nice to be able to directly compare BrainSeg (no partial >volume correction) with BrainSegNotVent (partial volume correction), is >this possible? Thanks! > >Chris Bell >University of Minnesota > > _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://mail.nmr.mgh.harvard.edu/mailman/listinfo/freesurfer The information in this e-mail is intended only for the person to whom it is addressed. If you believe this e-mail was sent to you in error and the e-mail contains patient information, please contact the Partners Compliance HelpLine at http://www.partners.org/complianceline . If the e-mail was sent to you in error but does not contain patient information, please contact the sender and properly dispose of the e-mail.
