1. A method comprising: (a) determining a candidate sagittal direction for a brain image, said brain image defined by brain volume data in a three-dimensional space associated with first, second and third directions, said first, second and third directions being orthogonal to each other, said candidate sagittal direction being the closest direction of said first, second and third directions to an actual sagittal direction, said determining said candidate sagittal direction comprising: defining a first three-dimensional volume of interest of said brain image; obtaining brain volume data in said first volume of interest for a first plurality of slices in said first direction; defining a second three-dimensional volume of interest of said brain image; obtaining brain volume data in said second volume of interest for a second plurality of slices in said second direction; defining a third three-dimensional volume of interest of said brain image; obtaining brain volume data in said third volume of interest for a third plurality of slices in said third direction; determining a measure for each slice of said first, second and third plurality of slices; for each of said first, second and third plurality of slices, plotting said measure for said each slice of said plurality of slices, sequentially along a plot axis corresponding to respective first, second and third directions, to produce first, second and third measure plots; and determining, from said first, second and third measure plots, which of said first, second and third directions is said candidate sagittal direction with a candidate plurality of slices associated therewith.