In vivo 3D visualization of normal pyramidal tracts in human subjects using diffusion weighted magnetic resonance imaging and a neuronavigation system.

We describe the potential of anisotropic diffusion weighted imaging to visualize the course of large cerebral fiber tracts. Five healthy volunteers were investigated at a field strength of 1.5 Tesla, employing a spin-echo diffusion weighted sequence with gradient sensitivity in six non-collinear directions to visualize the course of the pyramidal tracts. The pyramidal tracts were segmented and reconstructed for three-dimensional visualization. Reconstruction results together with a fusioned high resolution 3D T1 weighted image data set were available in a customized neuronavigation system. Origination in the primary motor cortex, convergence in the centrum semiovale, the posterior limb of the internal capsule, the cerebral peduncles, the splitting at the level of the pons, and the pyramidal decussation were identified in all subjects. Fiber tract maps might have the prospect of guiding neurosurgical interventions, especially when being linked to a neuronavigation system. Other potential applications include the demonstration of the anatomical substrate of functional connectivity in the human brain.