Hi.
I have been working with various structural MRI tools. Analysing the same subjects I also find the TIV estimate using Freesurfer is in general much smaller than the output from SIENAX and SPM (get totals). I do not know the reason for this, and I would also be happy if the SPM list could share their view upon this issue.
Thanks so much!
Turi
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Fra: SPM (Statistical Parametric Mapping) [mailto:[log in to unmask]] På vegne av Maria Serra Blasco
Sendt: 13. mai 2010 13:03
Til: [log in to unmask]
Emne: [SPM] TIV SPM vs Freesurfer
Hello SPMers,
I would llike to analyse normalized hippocampi segmented with FreeSurfer. However, to normalize the hippocampi I need to know the TIV. For the moment, I have calculated it in two different ways. The first one is using "get_totals" function of the SPM segmented images (wm+gm+csf) and the second one using the TIV given directly by FreeSurfer. These values should be similar, however, they are not:
Mean TIV value obtained with freesurfer: 1174 cmm3
Mean TIV value obtained with SPM (get_totals): 1706 cmm3
Should I consider the TIV calculated with get_totals like wm+gm only? Why is this TIV so big?
Thank you in advance,
--
Maria Serra
PIC (Port d'Informació Científica)
Campus UAB, Edifici D
E-08193 Bellaterra, Barcelona
Telf. +34 93 586 8232
www.pic.es
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