I would use the eTIV (or the sTIV in v8), but it is actually a philosophical question. If you normalize by the brain volume, you are testing a different hypothesis than if you normalize by the TIV.
On 6/27/2025 4:01 PM, Krystalyn Edwards-Calma wrote:
External Email - Use CautionAloha,
Mahalo for your response! What do you use for normalization between subjects?
Mālama Pono,
Krystalyn Edwards-Calma
On Jun 27, 2025, at 5:23 AM, Douglas N. Greve dgreve@mgh.harvard.edu wrote:
This is not necessarily a problem. The "e" in eTIV means "estimate". It is a slight hack where the registration to MNI space is used to compute an estimate of the TIV, so it is not based on a segmentation or any real image processing, so it is sometimes quite off. This ratio was really just meant to be a flag to catch your attention. Now that it has it, just look at the skull stripping and see if it looks ok. If it does, then ignore the flag.
On 6/25/2025 6:49 PM, Krystalyn Edwards-Calma wrote: External Email - Use Caution
Aloha,
I am using Version 7.4.1. After running recon-all for multiple subjects, I noticed the Brain mask is larger than the intracranial volume (Mask-to-eTIV > 1). I attempted multiple different skull stripping methods, however, the mask-to-eTIV is always > 1. Any suggestions on how to fix this? Mahalo for your help.
Malama pono,
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