Hello,
We are conducting a longitudinal study and are using TBSS to warp each FA
map to standard space. With our DTI data, we've found slightly more
intra-subject variability in the nonlinear warp than we were expecting.
In an attempt to address this variability, prior to running tbss_2, we
align the time-1 and time-2 data into a half-way space (just as is done in
SIENA). From there, we compute an average FA map for each subject (time-1 +
time2/2) and feed that image into tbss_2 to determine the nonlinear warp.
We can then apply this warp to the individual time-point images using
tbss_non_FA. This method seems to reduce the intra-subject variability by
using the same nonlinear warp for each time point.
My question then is, is there a way to find the "mid point" among 3+ scans,
just as is done in SIENA with 2 scans?
Best,
Ryan
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