A centerline extraction unit extracts at least two coronary artery centerline structures from at least two images respectively corresponding to at least two cardiac phases concerning a heart, an interpolation processing unit interpolates coronary artery centerline structures concerning other cardiac phases from the at least two extracted coronary artery centerline structures to generate coronary artery centerline structures respectively corresponding to a plurality of cardiac phases throughout one heartbeat of the heart, and a displacement distribution calculation unit calculates a plurality of displacement distributions between the respective cardiac phases from a plurality of coronary artery centerline structures throughout the one heartbeat.