Relationship between dcm xyz coordinate and nifti xyz coordinate

Hi Everyone!
I am dealing with converting the dcm world system coordinate to MNI space coordinate. I can get the transformation matrix of nifti to MNI by FSL FLIRT. However, I’m quite confused about the relationship between the dcm xyz coordinate and nifti xyz coordinate. What is the relationship between the dcm xyz coordinate and nifti coordinate? I’m using the GE scanner by the way. Thank you so much for any help you could offer!!