In some situations a patient who has undergone a functional PET might also have had a more "anatomical PET" (e.g. FDG). In this case, the "anatomical PET" should be used for the stereotactic normalization, and the resulting transformation applied to the functional PET. Essentially, the "anatomical PET" will take the role of the MRI in the PET-MRI workflow described above. In the following the "anatomical PET" series will be called "FDG PET".