11 Apr
2026
11 Apr
'26
7:55 p.m.
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Dear FreeSurfer experts,
I have a subject with good segmentation (aseg appears accurate, with no FOV truncation), but with substantial extracranial tissue, particularly neck tissue. The eTIV is relatively low (~1070 mL), and the MaskVol/eTIV ratio is high (~1.23). This subject also behaves as an outlier, showing artificially increased cortical volumes after normalization by eTIV.
What would be the recommended approach to obtain a more reliable eTIV in such a case?
 Many thanks, P.G.
