Hi Freesurfer team,

Thank you in advance for your help. We are attempting to obtain left hemisphere and right hemisphere volumes for various grey and white matter structures in a variety of controls and brain injured patients. However, values for the corpus callosum are often not reported in aparc.stats files for either hemisphere. This has occurred for both patients and normal controls. Is there a reason why these values are not being computed?

Also, in the aseg.stats for several patients, the Corpus Callosum mean values are reported as 0.0000 with SD, Min, and Max of 0 as well. Are the brains perhaps too structurally abnormal to report a reliable value? The subjects with this problem had a ventriculostomy, which damaged the corpus callosum to some extent. Should CC values for these patients be considered unusable? I have attached a T1-hdr file for your reference. In addition, I have attached the aseg.stats file for this subject(which reports a CC value of 0) and the lh.aparc.stats file (which did not report a corpus callosum value). If the ventriculostomy is to blame, can you provide a reason why for some normal controls the corpus callosum volume was not calculated for left and right hemispheres? Any insight you could provide would be greatly appreciated.

Thank you very much for your time and help,

Matt