1. An image data processor, comprising: a shape likelihood determiner configured to processes voxels of image data and determines a likelihood that a voxel represents predetermined tissue of interest for a plurality of the voxels based on a shape of a tissue represented by the voxel; an opacity determiner that configured to determines an opacity suppression for each of the plurality of voxels based on the likelihood; a re-formatter configured to re-formats the image data based on the determined opacity suppression, generating opacity suppressed re-formatted data; and a rendering engine that configured to visually presents the opacity suppressed re-formatted data.