Freesurfers,
So you can ignore this last question. I double-checked my addition and got 1046270 for the sum of all structures which is indeed more than BrainSegNotVent. Oops. Chris On Nov 3 2010, bell0...@umn.edu wrote: > > >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.
