Multiple sclerosis (MS), a neurological condition affecting around 2.9 million people globally, often results in permanent disabilities. A defining characteristic of MS is the immune system's attack on the myelin sheaths in the central nervous system. These sheaths act as insulation for nerve fibers, similar to plastic coating on a copper wire, ensuring swift and efficient electrical impulse transmission between nerve cells. Damage or thinning of these sheaths can cause irreversible issues with vision, speech, and coordination. Until now, visualizing the myelin sheaths effectively for reliable MS diagnosis and treatment has been challenging. Now, researchers have developed a new magnetic resonance imaging (MRI) technique that can map the condition of the myelin sheaths more accurately than was previously possible.

Traditional MRI machines provide only imprecise, indirect images of the myelin sheaths, as they generally respond to water molecules in the body activated by radio waves in a strong magnetic field. The myelin sheaths, comprising mainly fatty tissue and proteins, also contain trapped water, known as myelin water. Standard MRIs form images primarily using signals from the hydrogen atoms in this myelin water, instead of directly imaging the myelin sheaths themselves. A novel MRI approach developed by researchers at ETH Zurich (Zurich, Switzerland) addresses this issue by directly measuring myelin content. This method quantifies MRI brain images to show the relative myelin presence in specific areas. For example, a value of 8 indicates that the myelin content at that spot is just 8% of the maximum possible value, signifying considerable myelin sheath thinning.

The new technique enables doctors to assess the severity and progression of MS more accurately, as darker areas and lower numbers in the image correlate with greater reduction in myelin sheaths. However, imaging the sheaths directly poses challenges because the MRI-triggered signals in the tissue are short-lived, while those from myelin water are more enduring. The procedure has been successfully trialed on healthy individuals. Going forward, this specialized MRI system, complete with a dedicated head scanner, could assist physicians in early MS detection and in tracking disease progression more effectively. This technology not only has the potential to aid in new MS drug development but could also be used to better visualize other dense tissues such as connective tissue, tendons, and ligaments.

“Overall, myelin bilayer mapping has the potential to meet the myelin monitoring needs of clinical and research communities, be it for applications in basic research, diagnosis, disease monitoring, or drug development,” concluded the researchers. 

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