A plurality of sets of volume data obtained by imaging a subject on different imaging dates or different imaging times are analyzed, to calculate at least one type of index value that represents the state of the subject within each set of volume data. Transition data that represent transitions in the index values are generated for each type of index value, based on the calculated index values. At least one subject map (MAP) that includes a region in which transitions are detected is generated. Specified data (22a, 22b, 22c) from among the calculated index values and the generated transition data are correlated with regions (ROI1, ROI2, ROI3) within each subject map where transitions are detected, and output to a screen (73).
