Dear experts,

I would like to co-register T2 to T1 robustly, both images have a
resolution of 0.65mm3.

Firstly, I tried bbregister with the '--init-rr' flag, but this function
doesn't allow to keep the native voxel resolution (i.e., 0.65mm3),
changing it to 1 mm. As I wanted to maintain the native voxel
resolution , I tried the mri_robust_register function (corresponding to
the '--init-rr' flag) as explained in the help associated with this
function, but this process took thirteen hours:

EXAMPLE 4. Robust cross modal registration:

mri_robust_register --mov movT2.mgz --dst dstT1.mgz --satit --iscale

--mapmov T2_to_T1.mgz --lta T2_to_T1.lta --cost ROBENT --entradius 2

--entcorrection --weights T2_to_T1_weights.mgz

I also tried the standard cross modal registration. The process didn't
take as long, but the result was not as accurate as bbregister.

EXAMPLE 5. Standard cross modal registration:

mri_robust_register --mov movT2.mgz --dst dstT1.mgz --mapmov T2_to_

T1.mgz --lta T2_to_T1.lta --cost NMI

Could you suggest me how to accurately register T2 to T1 images
maintaining the native voxel resolution in a shorter time?

Thank you very much in advance.

Best,
Marina