An image guidance device comprising: a cone beam computed tomography, CBCT, imaging device; an electronic processor (20, 50); a display; and at least one non-transitory storage medium storing instructions readable and executable by the electronic processor to spatially register a liver imaged in a pre operative medical image and the liver imaged in a CBCT image acquired by the CBCT imaging device by performing a spatial registration process including: segmenting the surface of the liver in the CBCT image to generate a segmented surface of the liver in the CBCT image, and wherein the segmenting includes: performing occluded shape reconstruction using a statistical liver shape prior to reconstruct a missing or occluded portion of the segmented surface of the liver in the CBCT image; spatially registering the pre operative medical image and the CBCT image by warping one of the pre operative medical image and the CBCT image to the other of the pre operative medical image and the CBCT image using point set registration of a segmented surface of the liver in the pre operative medical image and the segmented surface of the liver in the CBCT image; and displaying, on the display, a fused image combining the warped one of the pre operative medical image and the CBCT image and the other of the pre operative medical image and the CBCT image. a cone beam computed tomography, CBCT, imaging device; an electronic processor (20, 50); a display; and at least one non-transitory storage medium storing instructions readable and executable by the electronic processor to spatially register a liver imaged in a pre operative medical image and the liver imaged in a CBCT image acquired by the CBCT imaging device by performing a spatial registration process including: segmenting the surface of the liver in the CBCT image to generate a segmented surface of the liver in the CBCT image, and wherein the segmenting includes: performing occluded shape reconstruction using a statistical liver shape prior to reconstruct a missing or occluded portion of the segmented surface of the liver in the CBCT image; spatially registering the pre operative medical image and the CBCT image by warping one of the pre operative medical image and the CBCT image to the other of the pre operative medical image and the CBCT image using point set registration of a segmented surface of the liver in the pre operative medical image and the segmented surface of the liver in the CBCT image; and displaying, on the display, a fused image combining the warped one of the pre operative medical image and the CBCT image and the other of the pre operative medical image and the CBCT image. segmenting the surface of the liver in the CBCT image to generate a segmented surface of the liver in the CBCT image, and wherein the segmenting includes: performing occluded shape reconstruction using a statistical liver shape prior to reconstruct a missing or occluded portion of the segmented surface of the liver in the CBCT image; spatially registering the pre operative medical image and the CBCT image by warping one of the pre operative medical image and the CBCT image to the other of the pre operative medical image and the CBCT image using point set registration of a segmented surface of the liver in the pre operative medical image and the segmented surface of the liver in the CBCT image; and displaying, on the display, a fused image combining the warped one of the pre operative medical image and the CBCT image and the other of the pre operative medical image and the CBCT image.