Group TDIs and/or VBA

Hi Rob,

Many thanks for your previous answer. I would appreciate if you or anyone else could help me with a couple of further related queries.

I’ve gone ahead with the first pipeline for qualitative evaluation that I outlined in my previous post. However, I am not sure about the output I am getting.

I have normalised my tracts with tcktransform as indicated in this post, which involves:

1- Generating xyz identity images in target space with warpinit
2- Applying inverse warps to these images (in SPM in my case)
3- Correcting and merge the IDwarps with warpcorrect
4- Normalizing tacts with tcktransform.

I then use tckmap to generate the TDI. The output of this, however, has three volumes. I assume I need only pay attention to the first volume? What are the other two volumes (I take it they are related to the identity images from warpinit and waprcorrect)?

Also, I am getting very large values in the TDI (100000+) (after normalising the tracts). FYI, prior to normalisation, I generated 10M streamlines from an ROI and then filtered them down to 8M with sift.

I am thankful for any insights in all this.

Juan

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