Dear all,

I’m processing data (anatomie and functional) of a longitudinal study on stroke patients and I have some questions concerning the VBM8 tool and DARTEL registration.

VBM8 :

- Can I use the batch for longitudinal data processing without having to do any changes or is there anything I should pay attention to.

- I’m not sure how I should enter the data in the batch. I have 3 time points for each subject. Do I have to enter the data of the 3 sessions together as a session or do I have to enter 3 sessions separatelly (select 3 times «New Session »). When I enter the data separatelly Dependencies change.

- Is it necessary to mask the lesion  to do.

DARTEL : I try to use DARTEL to register the anatomical and functional data of the 3 sessions together, but I don’t know if I did every thing correct. This is what I did :

- Skull stripping of session 1, 2 and 3 separatelly : as describe in the SPM manual page 318 Chapter 33 „Using DARTEL“

- Segmentation of the skull stripped T1 image of session 1, 2 and 3 separatelly : with New Segment

- Estimate warps (u_c1*.nii for each session) and Template of the 3 sessions (=Template6.nii): with Run DARTEL. I chose for Smoothing parameter None. I saw in previous studies that sometimes people do a mean image of all sessions. Is it correct to use instead the Template6.nii ?

- Normalisation : with Normalise to MNI space tool. Here I was not sure how to enter the flow fields. I chose to „Few Subjects“ and enter each session as a subject. So that I apply the flow field of the first session to the funtional scans of the first session, the flow field of the second session to the functional scans of the second session and so on. I run « Normalise to MNI space » tool ones for the functional scans with « preserve concentration » and FWHM=8 ;  and ones for the anatomical data (bias corrected image) with « preserve Amoun »t and FWHM=1.

- I’m not sure how to warp the sessions with each other in the DARTEL space. Can I just apply the warps that I got from Run DARTEL to the functional images? That means, can I warp the functional images of the first session with the flow field of the first session and the functional images oft he second session with the flow field of the second session, and so on.

- Again do I have to mask the lesion out to do the DARTEL normalisation.

I thank you very much for your help,

Natalia Estévez

Institute of Neuroradiology

University Hospital of Zurich

Switzerland