Scientists Propose New Standard for Imaging Myelin
By Pawel Slabiak • July 22, 2021
Center for Advanced Imaging Innovation and Research
Myelin insulates axons and facilitates transmission of electrical signals through the nervous system.
Damage and loss of myelin are linked to neurological diseases, such as Alzheimer's, multiple sclerosis, and Guillain-Barré syndrome.
To study myelination, scientists often use MRI or histology, but each method has limitations.
Histology gives a detailed view of tissue but destroys the sample through fixing, slicing, and staining.
MRI is noninvasive but it's also indirect and difficult to interpret at the microscopic scale.
Now, researchers have created a nondestructive way to image myelin by combining technologies used in particle physics and neuroscience.
The new method, called small-angle x-ray scattering tensor tomography (SAXS-TT), works by beaming focused x-rays through a tissue sample.
Myelin's periodic nanostructure alters the trajectories of beamed photons, revealing a ring-shaped "myelin peak."
Because myelin's nanostructure is directional, scientists can reconstruct its orientation and distribution in the brain with tensor tomography.
Researchers have demonstrated the new technique in mouse brain and spinal cord and in human brain tissue.
In a recent Nature Communications article, authors propose that SAXS-TT become "the reference method for myelin and axon orientation imaging."
brain of myelinated control mouse
brain of dysmyelinated "shiverer" mouse
Unique features of SAXS-TT include the ability to quantify myelination across whole samples and the ability to measure myelin's integrity...
...as well as the ability to distinguish myelin in the central nervous system from myelin in the peripheral nervous system.
Marios Georgiadis, who led the development of the new technique, got the idea while completing doctoral research at ETH Zurich.
"I was working on similar methods for bones," said Georgiadis. "We had these cool new tools to look at collagen fiber orientations."
He saw an opportunity to apply the same principles to neuroimaging.
The research has taken him from ETH Zurich to NYU Langone Health and Stanford University.
"The brain is the most interesting thing that is our there," Georgiadis said. "Everything we are is our brains."
Research images and videos courtesy of Marios Georgiadis. Axon artwork by Svitlana Pavliuk/Shutterstock. Text, media editing, and production by Pawel Slabiak.