1. A medical image processing apparatus, comprising: processing circuitry configured to implement registration on a medical image and each of a plurality of reference images; perform deformation on the medical image based on a result of the registration; set a first region of interest on the deformed medical image; set, on at least two of the plurality of reference images, a second region of interest corresponding to the first region of interest; and retrieve, from the reference images on which the second region of interest is set, a reference image similar to an image in the first region of interest.