Selecting an appropriate anisotropy index for displaying diffusion tensor imaging data with improved contrast and sensitivity

A review of the behavior of different diffusion anisotropy indices (DAIs) to changes in diffusion anisotropy was undertaken and the limitations of several previously proposed DAIs are discussed. A mathematical representation of anisotropy sensitivity was used to enable image contrast and sensitivity to noise to be predicted. This technique was utilized to devise a new DAI, the gamma‐variate anisotropy, which has a low sensitivity to noise and an improved contrast range for human brain imaging. This index can be easily modified for other applications, in that the range of anisotropy values to which it is highly sensitive can be altered. Magn Reson Med 44:117–121, 2000. © 2000 Wiley‐Liss, Inc.

[1]  P. Basser,et al.  Estimation of the effective self-diffusion tensor from the NMR spin echo. , 1994, Journal of magnetic resonance. Series B.

[2]  P. Basser,et al.  A simplified method to measure the diffusion tensor from seven MR images , 1998, Magnetic resonance in medicine.

[3]  J. Pekar,et al.  MR color mapping of myelin fiber orientation. , 1991, Journal of computer assisted tomography.

[4]  P van Gelderen,et al.  Water diffusion and acute stroke , 1994, Magnetic resonance in medicine.

[5]  P. Basser,et al.  MR diffusion tensor spectroscopy and imaging. , 1994, Biophysical journal.

[6]  M. Bastin,et al.  A theoretical study of the effect of experimental noise on the measurement of anisotropy in diffusion imaging. , 1998, Magnetic resonance imaging.

[7]  P. V. van Zijl,et al.  Orientation‐independent diffusion imaging without tensor diagonalization: Anisotropy definitions based on physical attributes of the diffusion ellipsoid , 1999, Journal of magnetic resonance imaging : JMRI.

[8]  J. Meyer,et al.  Functional brain imaging. , 1995, Journal of neurology, neurosurgery, and psychiatry.

[9]  P. Basser,et al.  Diffusion tensor MR imaging of the human brain. , 1996, Radiology.

[10]  M. I. Smith,et al.  A study of rotationally invariant and symmetric indices of diffusion anisotropy. , 1999, Magnetic resonance imaging.

[11]  D. Le Bihan.  Molecular diffusion nuclear magnetic resonance imaging. , 1991, Magnetic resonance quarterly.

[12]  P. Basser,et al.  Toward a quantitative assessment of diffusion anisotropy , 1996, Magnetic resonance in medicine.

[13]  P. Basser.  Inferring microstructural features and the physiological state of tissues from diffusion‐weighted images , 1995, NMR in biomedicine.

[14]  E. Akbudak,et al.  Encoding of anisotropic diffusion with tetrahedral gradients: A general mathematical diffusion formalism and experimental results , 1996, Magnetic resonance in medicine.

[15]  T Nakada,et al.  Magnetic resonance axonography of the rat spinal cord , 1994, Neuroreport.

[16]  M. Tamura,et al.  Interpretation of BOLD MRI Signals in Rat Brain Using Simultaneously Measured Near‐Infrared Spectrophotometric Information , 1996, NMR in biomedicine.

[17]  D M Doddrell,et al.  An evaluation of the time dependence of the anisotropy of the water diffusion tensor in acute human ischemia. , 1999, Magnetic resonance imaging.