Apparatus for mapping a structure in a body of a subject, comprising: an imaging device, adapted to capture a three-dimensional image of the structure comprising diagnostic information; a probe, adapted to be inserted into the structure, so as to generate a 3D geometrical map of the structure; a processor, coupled to the probe and the imaging device, and adapted to register the image with the map, such that each of a plurality of image points in the image is identified with a corresponding map point in the map; and a display, coupled to be driven by the processor to display the map, such that the diagnostic information associated with each of the image points is displayed at the corresponding map point, wherein the processor is adapted to: register the image with the map by applying a transformation to at least one of the image and the map so that following the transformation, the image and the map have a common axis and a common scale, divide the image into a plurality of parallel planar slices, perpendicular to the axis and mutually spaced along the axis, wherein the plurality of image points are located in the slices, and find an axial coordinate of each of the slices and an angular coordinate of each of the image points located in each of the slices, and to identify each of the image points with the map point having the same axial and angular coordinates. an imaging device, adapted to capture a three-dimensional image of the structure comprising diagnostic information; a probe, adapted to be inserted into the structure, so as to generate a 3D geometrical map of the structure; a processor, coupled to the probe and the imaging device, and adapted to register the image with the map, such that each of a plurality of image points in the image is identified with a corresponding map point in the map; and a display, coupled to be driven by the processor to display the map, such that the diagnostic information associated with each of the image points is displayed at the corresponding map point, wherein the processor is adapted to: register the image with the map by applying a transformation to at least one of the image and the map so that following the transformation, the image and the map have a common axis and a common scale, divide the image into a plurality of parallel planar slices, perpendicular to the axis and mutually spaced along the axis, wherein the plurality of image points are located in the slices, and find an axial coordinate of each of the slices and an angular coordinate of each of the image points located in each of the slices, and to identify each of the image points with the map point having the same axial and angular coordinates. register the image with the map by applying a transformation to at least one of the image and the map so that following the transformation, the image and the map have a common axis and a common scale, divide the image into a plurality of parallel planar slices, perpendicular to the axis and mutually spaced along the axis, wherein the plurality of image points are located in the slices, and find an axial coordinate of each of the slices and an angular coordinate of each of the image points located in each of the slices, and to identify each of the image points with the map point having the same axial and angular coordinates.