1. A method of determining an anterior commissure (AC) point and a posterior commissure (PC) point in a volumetric image, the method comprising: creating, by a computer, an edge mask of each of a plurality of axial image slices included in the volumetric image; identifying, by the computer, a symmetry axis of each edge mask; fitting, by the computer, a plane to the symmetry axes, the plane defining a mid-sagittal plane estimate; extracting, by the computer, a mid-sagittal image from the volumetric image based on the mid-sagittal plane estimate; and determining the AC point and the PC point in the mid-sagittal plane image.