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Hi, I am running Freesurfer on longitudinal datasets all obtained on 3T scanners. Unfortunately, many of the MRIs were done on different scanners, Phillips and GE. Would longitudinal pipeline help reduced scanner variability or should I process crossectionally each time point separately and normalize these time points with eTIV?
Many thanks AJ
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Hi AJ,
The longitudinal stream does not account for inter-scanner variability, but does reduce biases related to registering subsequent timepoints to the initial one.
Perhaps longitudinal experts could confirm, but I would run the longitudinal stream, then account for scanner differences afterwards.
-Paul
On Sun, Jul 4, 2021 at 10:03 AM AJ ajcns1969@gmail.com wrote:
External Email - Use CautionHi, I am running Freesurfer on longitudinal datasets all obtained on 3T scanners. Unfortunately, many of the MRIs were done on different scanners, Phillips and GE. Would longitudinal pipeline help reduced scanner variability or should I process crossectionally each time point separately and normalize these time points with eTIV?
Many thanks AJ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu https://secure-web.cisco.com/1NUSHcL-6MfXxf9NKeaB2MQFcyMAjYRVBfgF-8Tqm-hpRL5...
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Thank you for your response. Yes, the key question is to adjust for interscan variability through either histogram matching or ComBat before or after longitudinal run.
Will await to see what the longitudinal freesufer experts think.
My best AJ
On Wed, Jul 7, 2021, 11:40 Paul Wighton paul@corticometrics.com wrote:
External Email - Use CautionHi AJ,
The longitudinal stream does not account for inter-scanner variability, but does reduce biases related to registering subsequent timepoints to the initial one.
Perhaps longitudinal experts could confirm, but I would run the longitudinal stream, then account for scanner differences afterwards.
-Paul
On Sun, Jul 4, 2021 at 10:03 AM AJ ajcns1969@gmail.com wrote:
External Email - Use CautionHi, I am running Freesurfer on longitudinal datasets all obtained on 3T scanners. Unfortunately, many of the MRIs were done on different scanners, Phillips and GE. Would longitudinal pipeline help reduced scanner variability or should I process crossectionally each time point separately and normalize these time points with eTIV?
Many thanks AJ _______________________________________________ Freesurfer mailing list Freesurfer@nmr.mgh.harvard.edu *MailScanner has detected a possible fraud attempt from "secure-web.cisco.com" claiming to be* https://secure-web.cisco.com/1Siwhe86H-LigApCBD-7yQdMSJXDxcXQUEtfYz1F3QwHEah... https://secure-web.cisco.com/1NUSHcL-6MfXxf9NKeaB2MQFcyMAjYRVBfgF-8Tqm-hpRL5d5rFVDM0oAwSVo2R_PM0v-aN9yg9Qpq0JOr0-nqTEmq6kRBC64psI91YWhciSlRKGFz8C9eb_SP2bMSXWx2qzVD8i_2jgrnHauIB9P0MYG8JXOT9DxKxnExZ4p4ijMxt0zEOCI0qIdzD08_dShnSuqZ8FsRu1oSjBRq8JqTpm87BpKS6ufpv-MvPdFLLHOI-ioniUaR7gwaCCE-XmjIzWWo77VdI1FbFTJW-jw0A/https%3A%2F%2Fmail.nmr.mgh.harvard.edu%2Fmailman%2Flistinfo%2Ffreesurfer
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Paul Wighton