A diagnostic coordinate system has first through third axes based on a major axis and a minor axis of a follicle, the origin being the position of the center of gravity of the follicle. The diagnostic coordinate system is translated with respect to an XYZ display coordinate system, rotating the diagnostic coordinate system until the first axis corresponding to the major axis of the follicle overlaps the X-axis where the angle with the first axis is smallest, and rotating until the second axis corresponding to the minor axis of the follicle overlaps the Z-axis where the angle with the second axis is smallest. A tomographic image of the follicle is formed by an image in a plane that includes the Z and X axes, an image in a plane that includes the Y and Z axes, and an image in a plane that includes the X and Y axes.
