Age-related decline in brain white matter anisotropy measured with spatially corrected echo-planar diffusion tensor imaging

TLDR

Echo planar diffusion tensor imaging allows in vivo mapping of white matter tracts but suffers from field inhomogeneity‑induced geometric distortion. The study aimed to reduce spatial distortion by applying polynomial warping corrections and test their effects on fractional anisotropy in the genu and splenium of the corpus callosum. Spatial warping of non‑diffusion‑weighted EP images to long‑echo T2‑weighted fast spin echo images using a third‑order polynomial was performed, and the corrected images were used to assess age‑related changes in FA and intervoxel coherence across multiple white matter regions in 31 healthy men. FA decreased with age in all regions except the splenium, while intervoxel coherence increased with age in the genu. Published in Magn Reson Med 44:259–268 (2000); © 2000 Wiley‑Liss, Inc.

Abstract

Echo planar (EP) diffusion tensor imaging (DTI) permits in vivo identification of the orientation and coherence of brain white matter tracts but suffers from field inhomogeneity-induced geometric distortion. To reduce spatial distortion, polynomial warping corrections were applied and the effects tested on measures of fractional anisotropy (FA) in the genu and splenium of corpus callosum. Implementation entailed spatially warping EP images obtained without diffusion weighting (b = 0) to long-echo T2-weighted fast spin echo images, collected for anatomical delineation, tissue segmentation, and coregistration with the diffusion images. Using the optimal warping procedure (third-order polynomial), the effects of age on FA and a quantitative measure of intervoxel coherence (C) in the genu, splenium, centrum semiovale, and frontal and parietal pericallosal white matter were examined in 31 healthy men (23–76 years). FA declined significantly with age in all regions except the splenium, whereas intervoxel coherence positively correlated with age in the genu. Magn Reson Med 44:259–268, 2000. © 2000 Wiley-Liss, Inc.