Hi Alex, use the eTIV from the longitudinal subject. In theory, the size of the skull is not changing, and the longitudinal analysis gives you the best estimate of this unchanging number. doug
On 08/06/2013 06:00 PM, Alex Hanganu wrote:
Hello,
I am measuring the changes of subcortical volumes in a longitudinal study, so I took the volumes from longitudinal subjects (/name.long.base/). Now we need to perform the correction using the eTIV parameter, but the eTIV for longitudinal subjects for all time points is the same (/i//.e. eTIV for subject-time1.long.base = eTIV for subject-time2.long.base/)
Is it correct to perform the correction using the eTIV values from the longitudinal subjects, or we should use these measures from the cross-sectional corresponding subjects ?
Thanks,
Alex.
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