MRI Research Sheds New Light On Nerve Fibers In The Brain



World-leading experts in magnetic resonance imaging (MRI) from The University of Nottingham’s Sir Peter Mansfield Magnetic Resonance Centre have made a key discovery which could give the medical world a new tool for the improved diagnosis and monitoring of neurodegenerative diseases like multiple sclerosis.
The new study, published in the Proceedings of the National Academy of Science, reveals why images of the brain produced using the latest MRI techniques are so sensitive to the direction in which nerve fibers run.
The white matter of the brain is made up of billions of microscopic nerve fibers that pass information in the form of tiny electrical signals. To increase the speed at which these signals travel, each nerve fiber is encased by a sheath of myelin. Previous studies have shown that the appearance of white matter in MRI depends on the angle between the nerve fibers and the direction of the very strong magnetic field used in an MRI scanner.
Based on knowledge of the molecular structure of myelin, the Nottingham physicists devised a new model in which the nerve fibers are represented as long thin hollow tubes with anisotropic magnetic properties. This model explains the dependence of image contrast on fiber orientation in white matter and potentially allows information about the nerve fibers (such as their size and direction) to be inferred from magnetic resonance images.
Research Fellow Dr Samuel Wharton said: “While most MRI-based research focuses on tissue measurements at the millimeter length scale, our experimental scans on healthy human volunteers and modeling of the myelin sheath shows that much more detailed microscopic information relating to the size and direction of nerve fibers can be generated using fairly simple imaging techniques. The results will give clinicians more context in which to recognize and identify lesions or abnormalities in the brain and will also help them to tailor different types of scan to a particular patient.”
Dr Nikolaos Evangelou, Clinical Associate Professor specializing in multiple sclerosis at the Nottingham University Hospitals Trust said: "This research opens new avenues of looking at the nerve fibers in the brain. The more we understand about the nerves and the myelin around them, the more successful we are in studying brain diseases, such as multiple sclerosis [MS]. The recent advances in our understanding and treatments of MS are based on basic, solid research such as the one presented by Dr Wharton and Bowtell.”
The research will give scientists and clinicians all over the world a better understanding of the effects of nerve fibers and their orientation in MRI and has potentially useful applications in the diagnosis and monitoring of brain and nervous system diseases like multiple sclerosis where there are known links to myelin loss.
The full research paper "Fiber orientation-dependent white matter contrast in gradient echo MRI" by Dr Samuel Wharton and Professor Richard Bowtell is available here:http://www.pnas.org/.
Source: News Release
By: Amma Rayner
University of Nottingham
November 2, 2012

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