Not exactly because volumes are computed from soft segmentations rather than discrete labels, but yeah, it should be very close.
-- Juan Eugenio Iglesias http://www.jeiglesias.com
From: Marco Ganzetti marco.ganzetti@biogen.com Date: Tuesday, July 1, 2025 at 3:55 AM To: Freesurfer support list freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] Re: eTIV in SynthSeg
External Email - Use Caution Thanks. In SynthSeg, if I set a threshold at 0.5 on the segmentation output, should I get exactly the TIV? Label 0 is the background, therefore all the labels above 0 should constitute the TIV. Is this the case?
Best, Marco
From: Iglesias Gonzalez, Juan E. JIGLESIASGONZALEZ@mgh.harvard.edu Date: Tuesday, 1 July 2025 at 05:51 To: Freesurfer support list freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] Re: eTIV in SynthSeg EXTERNAL SENDER The former!
-- Juan Eugenio Iglesias http://www.jeiglesias.com
From: Marco Ganzetti marco.ganzetti@biogen.com Date: Monday, June 30, 2025 at 05:57 To: freesurfer@nmr.mgh.harvard.edu freesurfer@nmr.mgh.harvard.edu Subject: [Freesurfer] eTIV in SynthSeg
External Email - Use Caution Dear,
I would like to know how the eTIV is estimated in SynthSeg and SynthSeg+ . Is it a combination of CSF+ventricles+WM+GM masks? Or do you estimate is using the registration to MNI space approach?
Best, Marco