Hi Michelle,
when scanners (or even scanner hardware, like head coil or software
upgrades etc) change in a longitudinal study you will have difficulties
finding out whether the changes you see are real anatomical changes or
scanner effects. This is true for any software pipeline (longitudinal or
not). Often these changes are regional, not linear and not just offsets.
Often the seem to interact with disease, age etc (meaning they affect
older or more diseased subjects differently from young or healthy
subjects). Therefore even including a co-variate to correct for scanner
upgrade in the statistics may not be sufficient.
In your case you can either run the analysis only with the first three
time points. Or run it with all three and include a scanner covariate in
the statistic with interaction terms. In both cases you would profit
from using the longitudinal stream in Freesurfer.
Best, Martin
Am 05.09.2017 um 02:27 schrieb Michelle VanTieghem:
Hello,
Would it be ok to use the longitudinal pipeline for scans that were
acquired on different scanners (e.g time 1 and time 2 on the same
scanner, time 3 on different scanner)? Would the longitudinal pipeline
help to account for different scanners, since it creates the average
base image for all 3 time points? or is this not recommended?
Thank you,
Michelle
--
Michelle VanTieghem
PhD student in Psychology
Developmental Affective Neuroscience Lab
Columbia University
mrv2...@columbia.edu <mailto:mrv2...@columbia.edu>
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