1. A medical image diagnosis apparatus configured to assist an operator in choosing from plural cross-sectional images one that satisfies a predetermined condition based on review of an intersecting cross-sectional image, said apparatus comprising: digital signal processing circuitry and a display screen that are configured to calculate positions of a plurality of candidate images which are to be candidates for a first cross-sectional image from three-dimensional image data obtained by taking images of a heart, generate the candidate images from the three-dimensional image data according to the calculated positions of the candidate images, generate, from the three-dimensional image data, one or more second cross-sectional images each of which intersects the candidate images, and display in parallel on said display screen, the candidate images, as well as the second cross-sectional images on each of which information is superimposed, wherein the superimposed information indicates positional relationships between the candidate images and the second cross-sectional image, wherein the digital signal processing circuitry is configured to vary a manner in which the candidate images are displayed, in accordance with levels of probability that the positions of the candidate images satisfy said predetermined condition.