External Email - Use Caution Dear Freesurfer experts/developers,
I would greatly appreciate your help/response with the following questions/concerns. ---------- Forwarded message --------- From: JM <mj70...@gmail.com> Date: Wed, Oct 30, 2024 at 11:09 AM Subject: recon all data for classification between groups ! To: Freesurfer support list <freesurfer@nmr.mgh.harvard.edu> Dear FS experts, I have longitudinal data: Three time-points [T1-T3] with an interval of about 6 months between T1 and T2 and 6 months between T2 and T3 from a control group as well as from a clinical group (again three time-points [T1-T3] with an interval of about 6 months between T1 and T2 and 6 months between T2 and T3). Sample sizes are: - For control group: 48 (for T1), 36 (for T2) and 33 (for T3) - For clinical group: 38 (for T1), 33 (for T2) and 31 (for T3) I was wondering if it's fine to consider and combine three time-points within each group as independent samples for classification purposes (i.e., N = 117 (48+36+33) for the control group and N = 102 (38+33+31) for clinical group) between the two groups (based on brain morphometry measures). If so, I was wondering whether the recon-all should be done in the longitudinal way ( https://secure-web.cisco.com/1dNOHCl2MSH_yKn1dLwqkg767H0z716kQLlx7ce7bPg1Ozkk1dPR7PNmtQlIFH4EwEsYAY0-kP691owcbYQ4vBCwtWxBTq7rvvxlMYOHU2QlaYlBKpce-YUIpq7qTVlDPYe8qhx5laHqD6upsfM29ejeLktvhvP-smjf1v7J0RxcCMxOuEPSbnaDg1YBgCVyNaqvSqscpXpZ3AScvpo8r7XXqciHERsnyi3gAzZtcOBErz8NjdIjiKdWbxp8lAKUnVkDL_wQFTMrGkDm95oNfXsOM4byUWEx5Y0IBhHgrMDE2kEZus3Orev6p2uC6cFdewGYpy0LKNl7WR-qPKu8RDw/https%3A%2F%2Fsurfer.nmr.mgh.harvard.edu%2Ffswiki%2FLongitudinalProcessing) i.e., making it unbiased towards a specific time-point, OR, the recon all should be run cross-sectionally so that we can keep all the time-points independent from each other. Any detailed explanation/justification would be really helpful. Also, I would greatly appreciate the response at earliest convenience. Thanks, M
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