High−Resolution Line−Scan Diffusion−Tensor MRI of White Matter Fiber Tract Anatomy

BACKGROUND AND PURPOSE: MR diffusion tensor imaging permits detailed visualization of white matter fiber tracts. This technique, unlike T2−weighted imaging, also provides information about fiber direction. We present normal white matter fiber tract anatomy at high−resolution using line scan diffusion tensor imaging. METHODS: Diffusion tensor images in axial, coronal and sagittal sections covering the entire brain volume were obtained with line scan diffusion imaging in six normal volunteers. Images were aquired for b−factors 5 and 1,000 s/mm at a scan resolution of 1.7x1.7x4 mm. For selected regions, images were scanned at a reduced field of view with a spatial resolution of 0.9x0.9x3 mm. For each pixel, the direction of maximum diffusivity was computed and used to display the course of white matter fibers. RESULTS: Fiber directions derived from the diffusion tensor were consistent with known white matter fiber anatomy. The principal fiber tracts were well seen in all subjects. Namely visualized were: the arcuate fasciculus; the superior and inferior longitudinal fasciculus; the uncinate fasciculus; the cingulum; the external and extreme capsule; the internal capsule; the corona radiata; the auditory and optic radiation; the anterior commissure; the corpus callosum; the pyramidal tract; the gracile and cuneatus fasciculus; the medial longitudinal fasciculus; the rubrospinal, tectospinal, central tegmental, and dorsal trigeminothalamic tract; the superior, inferior, and middle cerebellar peduncle; the pallidonigral and strionigral fibers; as well as the root fibers of the oculomotor and trigeminal nerve.