Anatomy of brain-stem white-matter tracts shown by diffusion-weighted imaging

We acquired high-resolution MRI and anisotropically diffusion-weighted imag es (DWI) with direction-selective gradients of the brain stem in 20 healthy volunteers, to identify brain-stem structures such as white-matter tracts and nuclei which show diffusion anisotropy. After averaging and superpositi on of individual cuts, the images were projected onto appropriate plates of the Schaltenbrand and Wahren anatomical atlas. We identified 20 structures - white-matter tracts and some nuclei - with high contrast. The direction of fibres could be determined as areas of increased (parallel to) or decrea sed diffusion (perpendicular to the gradient). This study may contribute to understanding of the functional anatomy of the brain stem.