Assessing White Matter Microstructure in Brain Regions with Different Myelin Architecture Using MRI

PLoS One. 2016 Nov 29;11(11):e0167274. doi: 10.1371/journal.pone.0167274. eCollection 2016.

Abstract

Objective: We investigate how known differences in myelin architecture between regions along the cortico-spinal tract and frontal white matter (WM) in 19 healthy adolescents are reflected in several quantitative MRI parameters that have been proposed to non-invasively probe WM microstructure. In a clinically feasible scan time, both conventional imaging sequences as well as microstructural MRI parameters were assessed in order to quantitatively characterise WM regions that are known to differ in the thickness of their myelin sheaths, and in the presence of crossing or parallel fibre organisation.

Results: We found that diffusion imaging, MR spectroscopy (MRS), myelin water fraction (MWF), Magnetization Transfer Imaging, and Quantitative Susceptibility Mapping were myelin-sensitive in different ways, giving complementary information for characterising WM microstructure with different underlying fibre architecture. From the diffusion parameters, neurite density (NODDI) was found to be more sensitive than fractional anisotropy (FA), underlining the limitation of FA in WM crossing fibre regions. In terms of sensitivity to different myelin content, we found that MWF, the mean diffusivity and chemical-shift imaging based MRS yielded the best discrimination between areas.

Conclusion: Multimodal assessment of WM microstructure was possible within clinically feasible scan times using a broad combination of quantitative microstructural MRI sequences. By assessing new microstructural WM parameters we were able to provide normative data and discuss their interpretation in regions with different myelin architecture, as well as their possible application as biomarker for WM disorders.

MeSH terms

  • Adolescent
  • Adult
  • Brain / diagnostic imaging*
  • Brain / metabolism
  • Brain Mapping
  • Child
  • Diffusion Tensor Imaging
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Magnetic Resonance Imaging*
  • Male
  • Myelin Sheath / chemistry*
  • Myelin Sheath / metabolism
  • White Matter / diagnostic imaging*
  • White Matter / metabolism
  • White Matter / pathology
  • White Matter / ultrastructure
  • Young Adult

Grants and funding

This study was funded by the Medical Faculty of the University of Tübingen, Germany. We also acknowledge support by Deutsche Forschungsgemeinschaft (DFG) and Open Access Publishing Fund of the University of Tübingen, Germany. T.S. was funded by DFG grant SCHU 3040/1-1, G.E.H. by the Ministry of Science, Research and the Arts of Baden-Württemberg (Az: 32-771-8-1504.12/1/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.