A series of X-ray images having been input and a series of cross-sectional images having been acquired are associated with one another, and are stored as diagnostic information. From said diagnostic information, two pieces of diagnostic information including first diagnostic information and second diagnostic information are selected. Either a first representative cross-sectional image and a first representative X-ray image corresponding thereto, which are included in the selected first diagnostic information, or a second representative cross-sectional image and a second representative X-ray image corresponding thereto, which are included in the selected second diagnostic information, are displayed. In the displayed first representative X-ray image and second representative X-ray image, the position of a focus-of-observation site is designated. Frames corresponding to the designated position within a blood vessel are detected from each of the series of cross-sectional images including the first representative cross-sectional image, the series of X-ray images including the first representative X-ray image, the series of cross-sectional images including the second representative cross-sectional image, and the series of X-ray images including the second representative X-ray image. A comparative display of the first representative cross-sectional image, the second representative cross-sectional image, the first representative X-ray image, and the second representative X-ray image is displayed by the corresponding frames that have been detected.Selon linvention, une série dimages radiologiques qui ont été entrées et une série dimages de coupe transversale qui ont été acquises sont associées les unes aux autres et sont mémorisées en tant quinformations de diagnostic. À partir desdites informations de diagnostic, deux éléments dinformations de diagnostic comprenant des premières informations de diagnostic et des secondes informations de diagnostic sont sélectionnés. Soit un
