MRI BIOPHYSICS GROUP

bridging the micro-macro gap with diffusion MRI

In vivo observation and biophysical interpretation of time-dependent diffusion in human white matter.

TitleIn vivo observation and biophysical interpretation of time-dependent diffusion in human white matter.
Publication TypeJournal Article
Year of Publication2016
AuthorsFieremans, E, Burcaw, LM, Lee, H-H, Lemberskiy, G, Veraart, J, Novikov, DS
JournalNeuroimage
Volume129
Pagination414-427
Date Published01/2016
ISSN1095-9572
Abstract

The presence of micrometer-level restrictions leads to a decrease of diffusion coefficient with diffusion time. Here we investigate this effect in human white matter in vivo. We focus on a broad range of diffusion times, up to 600ms, covering diffusion length scales up to about 30 μm. We perform stimulated echo diffusion tensor imaging on 5 healthy volunteers and observe a relatively weak time-dependence in diffusion transverse to major fiber tracts. Remarkably, we also find notable time-dependence in the longitudinal direction. Comparing models of diffusion in ordered, confined and disordered media, we argue that the time-dependence in both directions can arise due to structural disorder, such as axonal beads in the longitudinal direction, and the random packing geometry of fibers within a bundle in the transverse direction. These time-dependent effects extend beyond a simple picture of Gaussian compartments, and may lead to novel markers that are specific to neuronal fiber geometry at the micrometer scale.

DOI10.1016/j.neuroimage.2016.01.018
Alternate JournalNeuroimage
PubMed ID26804782
Grant ListP30 AG008051 / AG / NIA NIH HHS / United States
R01 NS088040 / NS / NINDS NIH HHS / United States
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