A method is to be implemented by a computing device and includes steps of: a) identifying, according to a magnetic resonance imaging (MRI) image, brain image regions each of which contains a respective portion of diffusion index values of at least one diffusion index, which results from image processing performed on said at least one MRI image b) for each of the brain image regions, calculating a characteristic parameter based on the respective portion of the diffusion index values and c) diagnosing the brain examined with one of predetermined categories of the neurological disorder by performing classification on a combination of the characteristic parameters via a classifier.
