A diagnostic imaging system comprising: a first scanner for obtaining a first set of electronic data of a region of interest of a subject; a second scanner for obtaining a second set of electronic data of the region of interest of the subject; and a first reconstruction means for reconstructing the first set into a first scanner image representation in a first image space being a voxel-based cartesian grid image space or a pixel-based cartesian grid image space; characterised in that the diagnostic imaging system further comprises: a second reconstruction means for reconstructing the second set into a non-voxel space or non-pixel space second scanner image representation in a second image space not being a voxel-based cartesian grid image space or a pixel-based cartesian grid image space, wherein the second reconstruction means includes a process means for reconstructing the second set into spherically symmetric volume elements; and a converting means for directly converting the non-voxel space or non-pixel space second scanner image representation of the second set into a first image space second scanner image representation in an image space having the same Cartesian grid and having the same voxel or pixel size as the first scanner image representation. a first scanner for obtaining a first set of electronic data of a region of interest of a subject; a second scanner for obtaining a second set of electronic data of the region of interest of the subject; and a first reconstruction means for reconstructing the first set into a first scanner image representation in a first image space being a voxel-based cartesian grid image space or a pixel-based cartesian grid image space; characterised in that the diagnostic imaging system further comprises: a second reconstruction means for reconstructing the second set into a non-voxel space or non-pixel space second scanner image representation in a second image space not being a voxel-based cartesian grid image space or a pixel-based cartesian grid image space, wherein the second reconstruction means includes a process means for reconstructing the second set into spherically symmetric volume elements; and a converting means for directly converting the non-voxel space or non-pixel space second scanner image representation of the second set into a first image space second scanner image representation in an image space having the same Cartesian grid and having the same voxel or pixel size as the first scanner image representation. a second reconstruction means for reconstructing the second set into a non-voxel space or non-pixel space second scanner image representation in a second image space not being a voxel-based cartesian grid image space or a pixel-based cartesian grid image space, wherein the second reconstruction means includes a process means for reconstructing the second set into spherically symmetric volume elements; and a converting means for directly converting the non-voxel space or non-pixel space second scanner image representation of the second set into a first image space second scanner image representation in an image space having the same Cartesian grid and having the same voxel or pixel size as the first scanner image representation.