A method for determining whether there is an abnormality in a brain includes steps of: receiving a to-be-determined (TBD) 3D brain image; implementing the calibration procedure on the TBD 3D brain image; generating a first TBD image of WM, a second TBD image of GM, and a third TBD image of CSF based on a multi-voxel pattern of the TBD 3D brain image; and inputting the first TBD image of WM into a first DNN model, the second TBD image of GM into a second DNN model, and the third TBD image of CSF into a third DNN model to determine whether there is an abnormality in the white matter, the gray matter and the cerebrospinal fluid, respectively.