Dear SPM experts,

I have been trying to normalize several rat brain DTI data together using SPM5 with the following estimation parameters:
nonlinear regularization: 40
nonlinear iterations: 54
nonlinear frequency cutoff: 25

After the normalization, certain parts of the brain are not registered nicely while certain parts are acceptable (visually). So I am wondering if anyone could kindly tell me what sort of parameters I should change to improve the normalization?

Any help would be greatly appreciated.

Many thanks,