A storage unit stores four-dimensional image data indicative of an aged change in perfusion in a three-dimensional region including at least a part of a subject including a body axis thereof. A control unit analyzes a distribution of a TTP value of the perfusion concerning the coronal slice. The control unit calculates a difference value between the TTP values ON both sides sandwiching the body axis ON a straight line orthogonal to the body axis in the coronal slice. The control unit analyzes at least one of a distribution of the TTP value and a distribution of a characteristic value different from the TTP value in regard to a axial slice orthogonal to the coronal slice at a position of the straight line ON which a maximum value in a plurality of difference values calculated is calculated.
