Experimental studies of g-ratio MRI in ex vivo mouse brain

Neuroimage. 2018 Feb 15:167:366-371. doi: 10.1016/j.neuroimage.2017.11.064. Epub 2017 Dec 5.

Abstract

This study aimed to experimentally evaluate a previously proposed MRI method for mapping axonal g-ratio (ratio of axon diameters, measured to the inner and outer boundary of myelin). MRI and electron microscopy were used to study excised and fixed brains of control mice and three mouse models of abnormal white matter. The results showed that g-ratio measured with MRI correlated with histological measures of myelinated axon g-ratio, but with a bias that is likely due to the presence of non-myelinated axons. The results also pointed to cases where the MRI g-ratio model simplifies to be primarily a function of total myelin content.

Keywords: Diffusion; G-ratio; MRI; Microstructure; Myelin; Relaxometry.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Axons* / pathology
  • Axons* / ultrastructure
  • Brain / diagnostic imaging*
  • Brain / pathology
  • Disease Models, Animal
  • Magnetic Resonance Imaging / methods*
  • Mice
  • Mice, Knockout
  • Microscopy, Electron / methods*
  • Myelin Sheath* / pathology
  • Myelin Sheath* / ultrastructure
  • White Matter / diagnostic imaging*
  • White Matter / pathology