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Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla
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Magnetic Resonance Imaging of Multiple Sclerosis at 7.0 Tesla

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Imaging G-Ratio in Multiple Sclerosis Using High-Gradient Diffusion MRI and Macromolecular Tissue Volume

F Yu1, Q Fan2, Q Tian2

  • 1From the Division of Neuroradiology (F.Y.), Department of Radiology, University of Texas Southwestern Medical Center, Dallas, Texas Frank.yu@utsouthwestern.edu.

AJNR. American Journal of Neuroradiology
|November 8, 2019
PubMed
Abstract

Insights

The imaging g-ratio, calculated using advanced MRI techniques, shows promise as a biomarker for axonal and myelin loss in multiple sclerosis (MS). This metric may help track disease progression and therapeutic responses in MS patients.

Area of Science:

  • Neuroimaging
  • Biomarker Discovery
  • Multiple Sclerosis Research

Background:

  • Remyelination is a key therapeutic target in multiple sclerosis (MS).
  • Current imaging markers for MS remyelination are limited.
  • Accurate assessment of axonal and myelin integrity is crucial for MS management.

Purpose of the Study:

  • To evaluate high-gradient diffusion MRI and macromolecular tissue volume imaging for estimating axonal and myelin volume fractions.
  • To calculate the imaging g-ratio as a measure of myelin and axonal integrity in MS.
  • To explore the relationship between these imaging metrics and neurologic disability in MS patients.

Main Methods:

  • Utilized a 3T MRI scanner with high gradient strength and a multishell diffusion MRI protocol.
  • Quantified myelin volume fraction using macromolecular tissue volume imaging.
  • Estimated axonal volume fraction via a 3-compartment white matter model and calculated the imaging g-ratio.

Main Results:

  • The imaging g-ratio was significantly elevated in MS lesions compared to normal-appearing white matter (WM).
  • Axonal and myelin volume fractions were significantly reduced in MS lesions and normal-appearing WM compared to controls.
  • Disability scores in MS correlated significantly with reduced myelin and axonal volume fractions in normal-appearing WM.

Conclusions:

  • The imaging g-ratio demonstrates potential as a reliable imaging biomarker for assessing axonal and myelin loss in MS.
  • This metric could aid in monitoring disease progression and treatment efficacy in multiple sclerosis.
  • Advanced MRI techniques offer new avenues for understanding MS pathophysiology.

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