Improving relative anisotropy measurement using directional correlation of diffusion tensors

Shu Wei Sun, Sheng Kwei Song, Chung Yi Hong, Woei C. Chu, Chen Chang

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


A method employing directional correlation of the diffusion tensor, directional-correlation weighted relative anisotropy (DRA), was developed to improve the accuracy of estimated relative anisotropy (RA). The intravoxel directional correlation was established on the same voxel between two identically acquired diffusion tensor images, and the correlation coefficient derived from tensor dot product was employed as the weighting factor applied in the calculation of RA. The effect of noise influence was reduced since the random noise between repeated scans is not directionally correlated. The RA and the inter- and intravoxel DRA estimations were examined on rat brains in vivo. The background noise alters the direction of eigenvectors and the magnitude of eigenvalues. The dispersion angle between repeatedly obtained eigenvectors, representing the extent of directional alteration of eigenvectors, depends on the tissue anisotropy as well as the signal-to-noise ratio (SNR) of the source images. Current results demonstrate that the intravoxel DRA improves the accuracy of RA estimation, increases the relative contrast of gray and white matter, and avoids the partial volume effect commonly seen in the intervoxel operations.

Original languageEnglish
Pages (from-to)1088-1092
Number of pages5
JournalMagnetic resonance in medicine
Issue number6
StatePublished - 2001


  • Diffusion tensor imaging
  • Directional correlation
  • Eigenvectors
  • Noise influence
  • Relative anisotropy


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