Begre, S., Frommer, A., von Kanel, R., Kiefer, C., & Federspiel, A. (2007). Relation of white matter anisotropy to visual memory in 17 healthy subjects. Brain Research, 1168, 60-66.
"DTI measures diffusion-driven displacements of molecules during their
random path along axonal fibers, expressed as fractional anisotropy
(FA) or intervoxel coherence (IC) ranging from 0 (isotropic medium) to
1 (fully anisotropic medium). FA is a measure that quantifies the
degree to which diffusion differs in the three dimensions. IC considers
the degree of collinearity between the diffusion tensor of the
reference voxel and the adjacent voxels, and, in addition, guarantees a
better signal-to-noise ratio than the commonly used FA (Pierpaoli and Basser, 1996).
Hence, based on the determination of the similarity of orientation of
adjacent voxels, IC reflects a measure of connectivity, expressing
fiber coherence at the voxel level with a spatial sampling limited by
voxel size."
"To compute the difference of intervoxel coherence values between the low performer and the high performer group, a t-test
was computed for each voxel within the 3-D white matter template. To
identify volume-corrected regions, clusters were defined as 6 or more
neighboring voxels (6 mm3) exceeding the t-test value of 2.9 (P < .01). For each cluster, IC values were averaged and tabulated and Talairach coordinates (Talairach and Tournoux, 1988) of the centers of gravity were noted. Clusters were assigned to the underlying white matter using 3-D anatomical data."
============================================================================================ I can find little else on the subject, and I wondered, if IC is so superior to FA, why isn't it a commonplace dti measure?
Has anyone out there used this technique, and would you care to comment on it?
Thankyou,
Dianne
-- Dianne Patterson, Ph.D. [log in to unmask] ERP Lab
University of Arizona 621-3256 (Office)
