Dear freesurfer users, I have used freesurfer to segment hippocampal subfields. Then I used freeview to convert the derived .mgz files in .nii files for further analysis. I estimated the hippocampal subfields volumes with the command: kvlQuantifyPosteriorProbabilityImages $ FREESURFER_HOME/ data/ GEMS/ compressionLookupTable.txt  posterior_right_* posterior_Right-Hippocampus.mgz I have calculated the number of voxels in the converted .nii files using SPM and realized that they do not fit the estimated volumes through freesurfer Example for CA2-2 estimated voxel number though freesurfer:   6851 voxels found in .nii file: 15812 Did somebody had similar problems? Do you have any suggestion? Are there any incompatibilities between SPM and freesurfer? I did not find any apparent error in my counting script. Thank you very much and regards, Lorenzo Pasquini Can. Ph. D., Medical Life Science and Technology (Technische Universität Muenchen) Neuroimaging Lab, Neuroradiology Klinikum r. d. Isar (Technische Universität) 81675 München Tel.: 0049 (0) 89 4140-7666