Hello,
I'm learning to use freesurfer.
I would understand if the tissue that is not brain (i.e. meninges, vessel and skull), which is not automatically included in pial, must be deleted with the manual editing or not.
I send you some screenshots as exemple.
In this cases, I can ignore skull and vessel out of the pial surface or I have to delete them?
In this page ( http://freesurfer.net/fswiki/Edits ) they wrote : "Skull, dura and blood vessels might interfere with surface formation and need to be erased". Elsewhere they wrote that, in manual editing, leaving meninges it's not a skull strip error.  
In the manual editing of the brainmask.mgz, I obtain different  values of volumes (in the aseg.stats) if I delete skull, meninges and vessel or not.
thank you,
Irene