Inquiry regarding setting longitudinal variables in Correlational Tractography (Version: Apr 18 2026)

[이익성]

Hi Frank and DSI Studio Community,

I am currently conducting a longitudinal DTI study to compare DTI parameters before and after rehabilitation (ses-1 vs. ses-2).

I have successfully created a longitudinal database (ses2 - ses1) using the "Construct Longitudinal Database" tool. However, I am encountering an issue when trying to perform Correlational Tractography (Connectometry).

In the "Study Variables" section, I cannot find an option to explicitly set or recognize the "longitudinal change" as a variable.

My specific questions are:

1. To analyze the correlation between the longitudinal change (ses2-ses1) and other clinical scores, should I manually prepare and load a CSV or TSV file containing these variables?

2. If I use the longitudinal database (which already represents the difference), does DSI Studio automatically treat the input as the "change," or do I still need to define a baseline/offset variable?

Environment:

• DSI Studio Version: April 18, 2026

• Analysis: Longitudinal Connectometry (ses2 - ses1)

Any guidance on the correct workflow for defining study variables in a longitudinal setup would be greatly appreciated.

Best regards,

[Frank Yeh]

Sorry for the delayed reply.

> In the "Study Variables" section, I cannot find an option to explicitly set or recognize the "longitudinal change" as a variable.

When computing the longitudinal changes, if you filter the differences
to be positive or negative, then only one side of the changes remain
in the database, and the longitudinal change cannot be tested.

You may need to create a non filtered longitudinal database to test
longitudinal change. After testing and confirming there are
significant changes at one direction (increase or decrease), filter
data to keep that direction and correlate it with study variable.

>
> My specific questions are:
>
> To analyze the correlation between the longitudinal change (ses2-ses1) and other clinical scores, should I manually prepare and load a CSV or TSV file containing these variables?

Yes, this will make sure the variable matching is correct.

>
> If I use the longitudinal database (which already represents the difference), does DSI Studio automatically treat the input as the "change," or do I still need to define a baseline/offset variable?

Yes, only as "Changes". because only the changes are recorded in the database.

>
> Environment:
>
> DSI Studio Version: April 18, 2026
>
> Analysis: Longitudinal Connectometry (ses2 - ses1)
>
> Any guidance on the correct workflow for defining study variables in a longitudinal setup would be greatly appreciated.
>
> Best regards,
>

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