A diagnosis imaging apparatus and an operation method thereof are provided. The diagnosis imaging apparatus includes: an image processing apparatus for acquiring a first image including a first contour of a heart wall based on first image data of a heart of a subject acquired when the subject is subjected to a first stress intensity level, acquiring a second image including a second contour of the heart wall based on second image data of the heart of the subject acquired when the subject is subjected to a second stress intensity level, and acquiring a third image representing a difference between the first contour and the second contour based on the first image and the second image and a display apparatus for displaying the third image.
