A diffusion-weighted MRI pulse sequence employs a two-dimensional
diffusion weighting gradient that is sensitive to spin diffusion in a
plane defined by two orthogonal gradients to acquire an image. The
resulting magnitude image indicates the location of neuronal fibers
perpendicular to this plane and by repeating the acquisition with the
plane oriented at different angles, neuronal fibers extending through the
field of view at any angle are detected. The magnitude images are used to
produce a fiber tracking image.