Mirrow MRI image

Dear all,

I have the following problem:
I have an mri image and a mask. Both have the same dimensions but the x-axes of the mask is the other way around:

Bildschirmfoto 2020-09-08 um 17.59.28

So I tried to save my mask with another affine matrix (the one from the image):
mask = nib.Nifti1Image(mask, affine=image.affine)
nib.save(mask, (’/Users/neurolab//mask_affined.nii.gz’))

But when I mask later on my image left and right side are mirrored.

can be closed!
Thank you