Hi Mark,

Thanks for your answer.

I have a second question. When I process the registration within FDT GUI, Is it important to consider the fact that the voxel size is different between DTI and anatomic scans ? In other words, I should re-sample my scans or not ?

Thanks for your help,

Amandine




2011/8/30 Mark Jenkinson <[log in to unmask]>
Dear Amandine,

Please look at the FSL course material on registration and FDT, which explains
how to register images together and transform images between spaces.
You may find it convenient to use the FDT GUI to do your registration.

Once you have the registration done and transform the FIRST result into
the space of the MD image (and appropriately threshold it) then you can
calculate the MD values using fslmaths and fslstats.

All the best,
       Mark


On 29 Aug 2011, at 16:12, Amandine Pelletier wrote:

> Dear FSL users,
>
> I'm working on a cohort of 154 subjects, two types of scans were acquired : anatomical MRI and DTI scans. MD and FA indices were extracted from DTI images and analysed using Voxel-Based approach.
> I would like to work with a Region Of Interest approach. So, I have run hippocampal segmentation using FIRST. I have check the registrations using slicesdir, and then I obtained the hippocampal volumes for each subject.
> I would like to know if it's possible to use the hippocampal mask obtained in order to extracted MD values. I suppose that in a first time, I should coregister MD images to the 3D T1 for each subject but I don't know how...Knowing that, DTI scans have a resolution of 1x1x1 mm while anatomic scans have a resolution of 2x2x2 mm...
>
> I'm sorry, I'm not an expert for using FSL and so I have some difficulties...
>
> Thank for your time and your help,
>
> Amandine
>