Anisotropy in high angular resolution diffusion-weighted MRI

Magn Reson Med. 2001 Jun;45(6):935-9. doi: 10.1002/mrm.1125.


The diffusion in voxels with multidirectional fibers can be quite complicated and not necessarily well characterized by the standard diffusion tensor model. High angular resolution diffusion-weighted acquisitions have recently been proposed as a method to investigate such voxels, but the reconstruction methods proposed require sophisticated estimation schemes. We present here a simple algorithm for the identification of diffusion anisotropy based upon the variance of the estimated apparent diffusion coefficient (ADC) as a function of measurement direction. The rationale for this method is discussed, and results in normal human subjects acquired with a novel diffusion-weighted stimulated-echo spiral acquisition are presented which distinguish areas of anisotropy that are not apparent in the relative anisotropy maps derived from the standard diffusion tensor model. Published 2001 Wiley-Liss, Inc.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Algorithms
  • Anisotropy
  • Brain / anatomy & histology*
  • Diffusion
  • Humans
  • Image Enhancement*
  • Image Processing, Computer-Assisted*
  • Magnetic Resonance Imaging*
  • Reference Values