Registration-based interpolation between images slices is provided. In various embodiments, a plurality of 2D images is read. Each of the plurality of 2D images represents a slice of a 3D volume. A plurality of annotations is read for a subset of the plurality of 2D images. The annotations comprise at least one anatomical label. 2D images lacking annotations are selected from the plurality of 2D images. The at least one anatomical label is propagated from the subset of the plurality of 2D images to the selected 2D images by deformable registration.