A non-invasive medical imaging system includes: an imaging scanner capable of generating an imaging signal from a subject under observation inside the imaging scanner; a signal processing system in communication with the imaging scanner, and a data storage unit in communication with the signal processing system, wherein the data storage unit is suitable for storing a first image corresponding to a tissue region of the subject, wherein the signal processing system is capable of generating a second image encoding the tissue region of the subject by performing a reconstruction based on the imaging signal, the imaging signal acquired at a later time than the first image; wherein the signal processing system is constructed to receive the imaging signal from the imaging scanner and the first image from the data storage unit respectively, wherein the signal processing system is adapted to provide a registered first image by registering the first image to the second image via a transformation in a space of diffeomorphism, wherein the signal processing system is further adapted to compute a difference image between the second image and the registered first image; and wherein the signal processing system is further adapted to output the difference image.