An X-ray CT image of a low spatial resolution image is acquired by employing a PET-X-ray CT examination apparatus. Also, a PET image is acquired by employing the PET-X-ray CT examination apparatus. Furthermore, an X-ray CT image of a high spatial resolution image is acquired by employing another X-ray CT examination apparatus. Then, the X-ray CT image equal to the low spatial resolution image is corrected by employing the X-ray CT image, so that an X-ray CT image equal to a high spatial resolution image is obtained. Since a positional relationship of the resulting X-ray CT image with respect to the PET image can be grasped, this PET image can be simply synthesized with the X-ray CT image like an image.