Diffusion anisotropy color-coded map of cerebral white matter: quantitative comparison between orthogonal anisotropic...

Area of Science:

• Neuroimaging
• Diffusion MRI techniques

Background:

• Diffusion anisotropy color-coded maps of cerebral white matter are generated using the three-dimensional anisotropy contrast (3DAC) technique.
• The precision of 3DAC has not been fully validated.

Purpose of the Study:

• To determine if 3DAC is comparable to diffusion tensor imaging (DTI) color maps for visualizing white matter.
• To validate the precision of 3DAC in neuroimaging.

Main Methods:

• Generated color-coded maps using 3DAC and DTI (primary eigenvector [e1] and fractional anisotropy [FA]) from identical datasets in 15 healthy individuals.
• Evaluated the directional difference (θ) between 3DAC and e1 in cerebral white matter.
• Examined correlations between θ and FA or e1 obliqueness.

Main Results:

• Significant negative and positive correlations were found between θ and FA values or e1 obliqueness, respectively.
• White matter tracts with high FA/low obliqueness (pyramidal tract, cingulum, corpus callosum) showed similar coloration and significantly smaller θ compared to the entire white matter.
• Specific θ values for pyramidal tract, cingulum, and corpus callosum were 4.4° ± 1.6°, 9.3° ± 2.8°, and 11.2° ± 1.1°, respectively, versus 13.9° ± 1.1° for entire white matter.

Conclusions:

• 3DAC effectively visualizes white matter tract directional information with precision comparable to DTI-based color maps.
• 3DAC accuracy is particularly high when fractional anisotropy (FA) is large and/or eigenvector directions are orthogonal.