Inconsistent connectivity matrix results

[Gabriela Epihova]

Dear Frank,

I am running tractography on fetal scans. I run whole brain tracking for each scan and then create a connectivity matrix for each scan (mapped to the neonatal ICL_GM atlas). Then I get an average across all subjects. 

However, when I create a connectometry database (using the dHCP) template from the same subjects and create a group connectivity matrix of the same atlas (ICL_GM) I get different results. Would you have any idea why that is? - my logic is that because both times individual scans are normalized to the dHCP_neonate, the results shouldn't be different. All other tracking parameters I use are the same. Which option would you recommend me using? 

Thanks in advance :)

Best,

Gabriela

[Frank Yeh]

I am running tractography on fetal scans. I run whole brain tracking for each scan and then create a connectivity matrix for each scan (mapped to the neonatal ICL_GM atlas). Then I get an average across all subjects. 

I usually do not recommend this approach.

 

However, when I create a connectometry database (using the dHCP) template from the same subjects and create a group connectivity matrix of the same atlas (ICL_GM) I get different results. Would you have any idea why that is?

The tracking on the connectometry database will be just a simple tracking on the template. It is not using the database at all.

 

- my logic is that because both times individual scans are normalized to the dHCP_neonate, the results shouldn't be different. All other tracking parameters I use are the same. Which option would you recommend me using? 

I would suggest the workshop videos at practicum.labsolver.org about how to use connectometry database, and why whole-brain tractography is not ideal.

Best regards,

Frank

 

Thanks in advance :)

Best,

Gabriela

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[Gabriela Epihova]

Hi Frank,

Many thanks for your quick reply. 

I see.. Still I would expect similar results in the tractography of the template to the tractography of individual fetal brains. Anyway -- I figured my mistake - I was aligning the ROIs but the brains weren't in the right orientation. Fixed it now and it makes much more sense. 

Whole brain tractography might not be ideal but I find it works well for creating connectomes. Especially, given that there are no atlases of tracks at that developmental stage. 

Thanks again for all your help and supporting the community : )

Best,

Gabriela