A medical information processing apparatus according to an embodiment includes processing circuitry. The processing circuitry collects pieces of past image data in a plurality of time phases that contain at least a part of a coronary artery of a heart and new image data in one time phase that contains at least a part of the coronary artery and has been acquired after acquisition of the pieces of past image data. The processing circuitry performs registration processing between the pieces of collected past image data and registration processing between any one of the pieces of past image data and the new image data. The processing circuitry generates pieces of synthesized image data corresponding to the time phases of the pieces of past image data other than the past image data on which the registration processing with the new image data has been executed by reflecting a shape of the new image data based on results of the registration processing. The processing circuitry derives a fluid parameter related to the coronary artery by executing fluid analysis using the pieces of synthesized image data.
