Improved sensitivity to cerebral white matter abnormalities in Alzheimer's disease with spherical deconvolution based tractography

PLoS One. 2012;7(8):e44074. doi: 10.1371/journal.pone.0044074. Epub 2012 Aug 31.

Abstract

Diffusion tensor imaging (DTI) based fiber tractography (FT) is the most popular approach for investigating white matter tracts in vivo, despite its inability to reconstruct fiber pathways in regions with "crossing fibers." Recently, constrained spherical deconvolution (CSD) has been developed to mitigate the adverse effects of "crossing fibers" on DTI based FT. Notwithstanding the methodological benefit, the clinical relevance of CSD based FT for the assessment of white matter abnormalities remains unclear. In this work, we evaluated the applicability of a hybrid framework, in which CSD based FT is combined with conventional DTI metrics to assess white matter abnormalities in 25 patients with early Alzheimer's disease. Both CSD and DTI based FT were used to reconstruct two white matter tracts: one with regions of "crossing fibers," i.e., the superior longitudinal fasciculus (SLF) and one which contains only one fiber orientation, i.e. the midsagittal section of the corpus callosum (CC). The DTI metrics, fractional anisotropy (FA) and mean diffusivity (MD), obtained from these tracts were related to memory function. Our results show that in the tract with "crossing fibers" the relation between FA/MD and memory was stronger with CSD than with DTI based FT. By contrast, in the fiber bundle where one fiber population predominates, the relation between FA/MD and memory was comparable between both tractography methods. Importantly, these associations were most pronounced after adjustment for the planar diffusion coefficient, a measure reflecting the degree of fiber organization complexity. These findings indicate that compared to conventionally applied DTI based FT, CSD based FT combined with DTI metrics can increase the sensitivity to detect functionally significant white matter abnormalities in tracts with complex white matter architecture.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged, 80 and over
  • Alzheimer Disease / pathology*
  • Alzheimer Disease / physiopathology
  • Cerebrum / abnormalities*
  • Cerebrum / pathology*
  • Cerebrum / physiopathology
  • Cognition
  • Corpus Callosum / pathology
  • Corpus Callosum / physiopathology
  • Diffusion Tensor Imaging / methods*
  • Female
  • Humans
  • Male
  • Memory
  • Nerve Fibers, Myelinated / pathology

Grant support

The research of GJB is supported by a high potential grant from Utrecht University and VIDI grant 91711384 from ZonMw, The Netherlands Organisation for Health Research and Development. The research of AL is supported by the project Care4Me (Cooperative Advanced REsearch for Medical Efficiency) in the framework of the EU research programme ITEA (Information Technology for European Advancement). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.