[Freesurfer] bbregister: PET and MRI

Dear FS Team,

I have a problem with the bbregister command. I used it for coregister a MRI with a PET. My first step is set the same origin and orientation for both images (approximately) (I use SPM or tkregister2). After, I write in the terminal "bbregister --mov s24PET.img --t1 --s sr24 --init-fsl --reg register.dat"(s24 is the name of my patient) The result of the process is a bad corregister (see the included file).

I would like to improve this result. Maybe the number of iterations is too less (I'm not sure of that) I probed with the flags SPM, FSL and HEADER but they don't provide good result.

Thank you all in advance.