vat_wm_region_merge
=====================================================

.. py:function:: petpal.preproc.segmentation_tools.vat_wm_region_merge(wmparc_segmentation_path: str, out_image_path: str, wm_ref_segmentation_path: str, bs_segmentation_path: str = None)

   Merge subcortical structures into a merged segmentation image according to
   the protocol for processing the VAT radiotracer.

   :param wmparc_segmentation_path: Path to `wmparc` segmentation generated
                                    by FreeSurfer.
   :type wmparc_segmentation_path: str
   :param out_image_path: Path to which output fused segmentation is saved.
   :type out_image_path: str
   :param wm_ref_segmentation_path: Path to eroded white matter reference
                                    region generated by :meth:`vat_wm_ref_region`.
   :type wm_ref_segmentation_path: str
   :param bs_segmentation_path: Path to brainstem segmentation generated by
                                FreeSurfer. If None, then skip.
   :type bs_segmentation_path: str