Longitudinal Fixel-Based Analysis in Paediatric Temporal Lobe Epilepsy surgery

[luislacerda]

Hi Rob,

First of all, thank you so much for the time you spent getting back to me - it is really appreciated.

@rsmith

If your questions are “how does left temporal lobectomy change the brain white matter” and “how does right temporal lobectomy change the brain white matter”, then having them as two separate cohorts makes sense

I might end up considering the more general question of whether temporal lobectomy changes the brain white matter, but my main question is whether those changes will be different depending on the operated hemisphere.

@rsmith

So personally I’d be using a common response function across the two, as the alternative may be the source of limitations at a later date.

Understood.

@rsmith

You can also utilise masking within mrregister to prevent certain areas from driving the registration.

@rsmith

You would need some form of evidence that for your specific data, deviating from FOD-based registration because of the presence of resection provides sufficient benefit to justify doing so.

Ahh, I didn’t know this - Yep I will definitely try FOD-based registration and compare to what I already have and draw my conclusions then.

@rsmith

I’m failing to see the distinction between the two cases you describe here: both involve a single FOD template image, pre- and post-surgical data, and transformation of FOD data onto that template. What is the intended difference between “do a standard FBA … in one template” versus “create a midway template and project the FODs to that”?

I didn’t express myself very well here - I was probably just thinking of the design that I would apply and whether I should consider any difference images before creating the template. But I think it is better to keep things simple for now.

@rsmith

Here, I would firstly ask about the time period between resection and scan. If you were to scan the subject immediately after resection, then in comparison to the pre-surgical scan, one would expect the resected area to “disappear” and for the “connected” regions to not show any difference. In this case, if the resected region were included in the processing mask, then observation of a statistically significant effect external to the resected area would essentially be an artifact of the smoothing / statistical enhancement.

That was my intuition, but it makes more sense now!

@rsmith

If you want to go even further down this rabbit hole, that probably becomes a private conversation, as I’m now in an Epilepsy lab and would need to resolve such against my own plans.

It sounds good! At the moment, I will give it a go with all your useful suggestions and mature my research hypothesis, but I will be sure to reach out if/when it all starts making more sense.

Thank you very much on again.

Cheers

Luís