Multiple Sclerosis: MRI shows brain iron link

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  • Published: Aug 1, 2018
  • Author: David Bradley
  • Channels: MRI Spectroscopy
thumbnail image: Multiple Sclerosis: MRI shows brain iron link

Predicting MS disability

Image shows voxelwise analysis of quantitative susceptibility maps within thalamus, caudate, globus pallidus, and putamen comparing all participants with multiple sclerosis (MS) to healthy control (HC) participants. Areas of higher susceptibility in participants with MS compared with HC participants are shown in red-yellow. Areas of lower susceptibility in participants with MS compared with HC participants are shown in blue-light blue. Credit: Radiological Society of North America (RSNA)

Researchers at the University at Buffalo in Buffalo, New York, USA have used a magnetic resonance imaging (MRI) technique, quantitative susceptibility mapping, to measure the concentration of iron in the brains of multiple sclerosis patients. They examined 600 patients, 452 with early-stage disease, and 148 with more advanced disease, and found that when compared with the control group, the MS patients had higher levels of iron in the basal ganglia and lower levels of iron in the thalamus.

MS is a disease that attacks three critical components of the central nervous system, the team reports. The neurons, myelin (the protective, insulating sheath around the neurons), and the cells that produce myelin. Symptoms such as weakness, spasticity, and pain are the most common presentation and the disease can progress in many patients leaving them severely disabled. According to Buffalo's Robert Zivadinov, brain atrophy (shrinking) is the current gold standard for predicting cognitive and physical decline in MS, but it has limitations.

“Brain atrophy takes a long time to see,” he explains. “We need an earlier measure of who will develop MS-related disability.”

Iron highs and lows

That measure may now be possible thanks to a new, highly accurate MRI technique that can monitor iron levels in the brain and help identify which patients are at higher risk of for developing severe physical disability.

Iron is an essential element for many physiological functions, perhaps most obviously as being at the core of the oxygen-carrying haemoglobin molecule in our blood, but also in various liver enzymes essential for metabolism. It is also at the heart of various cellular functions in the brain, including myelination of neurons. Iron overload and iron deficiency can both be harmful.

“It is known that there is more iron in the deep gray matter structures in MS patients," explains Zivadinov, "but also we’ve seen in recent literature that there are regions where we find less iron in the brains of these patients. He and his colleagues have now compared brain iron levels in people with MS to those of a healthy control group. Those brain regions with more iron have a higher magnetic susceptibility, and those with lower iron concentrations have lower susceptibility, which shows up well in their MRI.

Testing times

The basal ganglia are a group of structures deep in the brain that are central to movement and the team found higher levels of iron in these structures in MS patients. However, MS patients showed lower levels of iron in the thalamus, which is an important brain region for processing sensory input. The thalamus acts as a relay between certain brain structures and the spinal cord. The team suggests that the lower iron content in the thalamus and higher iron content in other deep gray matter structures of people with MS is correlated with longer disease duration, higher disability degree and disease progression. The team found that the connection between iron concentration and disability was strong even once they had compensated for changes in the brain volumes of each individual structure.

“In this large cohort of MS patients and healthy controls, we have reported, for the first time, iron increasing in the basal ganglia but decreasing in thalamic structures,” Zivadinov explains. “Iron depletion or increase in several structures of the brain is an independent predictor of disability related to MS.” This MRI technique could be useful in monitoring the effects of new drugs being tested in MS patients. The current therapies are anti-inflammatory drugs but do not preclude the seemingly inevitable disability that comes with MS.

Related Links

Radiol 2018, online: "Brain Iron at Quantitative MRI Is Associated with Disability in Multiple Sclerosis"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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