I have two questions"
1. the type of aparc+aseg.mgz file is INT(1). after save_mgh(v, 'aparc+aseg82regions.mgz',M,mr); I find the type of aparc+aseg82regions.mgz is FLOAT (3). How to save aparc+aseg82regions.mgz file in INT ?

2. I want to convert the aparc+aseg82regions.mgz to .nii file (in native space)

I use the following command lines:
mri_label2vol --seg aparc+aseg82regions.mgz --temp rawavg.mgz --o aparc+aseg82regions-rawavg.mgz --regheader aparc+aseg82regions.mgz
mri_convert -odt int aparc+aseg82regions-rawavg.mgz aparc+aseg82regions-rawavg.nii

after these, I found the dimension is changed from 256*256*256 to 176*204*200.

Volume information for aparc+aseg82regions.mgz
          type: MGH
    dimensions: 256 x 256 x 256
   voxel sizes: 1.0000, 1.0000, 1.0000
          type: FLOAT (3)
           fov: 256.000
           dof: 1

Volume information for aparc+aseg82regions-rawavg.mgz
          type: MGH
    dimensions: 176 x 204 x 200
   voxel sizes: 1.0000, 1.0000, 1.0000
          type: INT (1)
           fov: 204.000
           dof: 0

Volume information for aparc+aseg82regions-rawavg.nii
          type: nii
    dimensions: 176 x 204 x 200
   voxel sizes: 1.0000, 1.0000, 1.0000
          type: INT (1)
           fov: 176.000
           dof: 0

I guess I must have done something wrong. But I can not figure out.

Best,

Jinsong