Hi Ruthi,
it is possible to add time points retrospectively without re-creating the base. However this will likely induce a processing bias, as the 3rd time point is treated differently from the first two. How big that is going to be nobody knows (it depends on your data and on the number of time points). The more time points are in the base, the less of a problem it should be, but with only 2, adding a 3rd may not be good.
Here is how you can do it recon-all -long <tpNsubjid> <longbasesubjid> -addtp -all but I recommend against it. If you do, you definitely need to describe this in the publication as it is not the standard procedure. You should also run several cases (maybe ones that did not need edits) separately with 3 time points in the base and test for differences.
The re-creation of the base is the biggest problem in unbiased longitudinal processing, but necessary to ensure all time points undergo exactly the same treatment.
Best, Martin
On Oct 8, 2015, at 4:40 PM, Adam, Ruth Ruth.Adam@med.uni-muenchen.de wrote:
Dear all,
We have run recon-all longitudinal stream on two time points and now have an additional time point we would like to integrate. Since edits and analysis were already done using the 2 time points template, we would like to avoid creation of a new template (by combining all time points) and instead register the third time point to the pre-existing template. What is the best way to do so? Is there a way to force recon-all to use a specific template?
Many thanks!
Best, ruthi
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