A method for myelin fiber orientation mapping using diffusion-weighted MR images

Magn Reson Imaging. 1994;12(3):443-54. doi: 10.1016/0730-725x(94)92538-0.

Abstract

In the past, the anisotropic diffusion of water molecules in white matter in the brain has been correlated to the basic symmetry of the myelin fibers: water diffuses more readily along the fiber direction than perpendicular to it. As a consequence, diffusion sensitized magnetic resonance imaging can be expected to be useful for studying the fiber orientation. In this work, we present a method for exploiting this type of information to map the fiber orientations in the image plane. It makes use of three diffusion-weighted images with sensitizing gradients along x, y and u, an axis at 45 degrees with respect to x and y. The orientation information contained in these images is summarized in a single image representing the angle between the fiber direction and a fixed axis, making use of a cyclic color scale. The method is evaluated using computer simulations for a variety of diffusion weighting strengths and signal-to-noise ratios, tested on a phantom and illustrated on an in vivo example. An extension to the determination of the fiber orientation in three dimensions is also described.

MeSH terms

  • Anisotropy
  • Brain / cytology*
  • Computer Simulation
  • Humans
  • Image Processing, Computer-Assisted
  • Magnetic Resonance Imaging* / methods
  • Models, Structural
  • Nerve Fibers, Myelinated*