vat_wm_ref_region
===================================================

.. py:function:: petpal.preproc.segmentation_tools.vat_wm_ref_region(input_segmentation_path: str, out_segmentation_path: str | None) -> ants.ANTsImage

   Generates the cortical white matter reference region described in O'Donnell
   JL et al. (2024).

   Reference: O'Donnell JL et al. (2024). PET Quantification of [18F]VAT in Human Brain and Its
   Test-Retest Reproducibility and Age Dependence. J Nucl Med. 2024 Jun
   3;65(6):956-961. doi: 10.2967/jnumed.123.266860. PMID: 38604762; PMCID:
   PMC11149597.

   Requires FreeSurfer segmentation with original label mappings.

   :param input_segmentation_path: Path to segmentation on which white
                                   matter reference region is computed.
   :type input_segmentation_path: str
   :param out_segmentation_path: Path to which white matter reference
                                 region mask image is saved.
   :type out_segmentation_path: str

   :returns: *wm_erode (ants.ANTsImage)* -- Eroded white matter reference region mask image.