Research News

Researchers from the Department of Biomedical Engineering have found that several magnetic resonance imaging (MRI) modalities can be harnessed to better assess the severity and progression of multiple sclerosis (MS) than traditional imaging methods, according to new findings from Kunio Nakamura, PhD, published in Multiple Sclerosis Journal. 

“Standard MRI methods are not specific enough to provide a complete picture of MS disease progression, especially in detecting damage within the cerebral cortex caused by cortical lesions,” said the study’s first author Yufan Zheng, PhD, who is a postdoctoral fellow in Dr. Nakamura’s lab.  

A hallmark of MS is demyelination, where the protective coating that helps transmit nerve impulses (called myelin) breaks down. In patients with MS, myelin loss is particularly difficult to detect in the brain’s outermost layer (the cerebral cortex), even with advanced MRI techniques. “We undertook this study to quantify how well these MRI techniques improve cortical lesion discovery.” 

Measuring the loss of myelin and the growth of lesions 

The researchers tested how well three currently available MRI modalities—MTR (magnetization transfer ratio), T1T2R (T1-weighted/T2-weighted ratio) and T2w (T2-weighted)—could determine areas of demyelination. They performed post-mortem MRIs utilizing the advanced modalities on nine subjects who had primary or secondary progressive MS. After the MRIs, researchers studied tissue samples from the cerebral cortices of each brain to determine how accurate the imaging techniques were in detecting demyelination. 

Expanding the potential of MRI 

Of the three modalities, T2w was the most accurate in determining areas of demyelination (71%), followed by T1T2R (42%) and MTR (39%). T2w also had the highest specificity (46%) in detecting demyelination, based on the amount of myelin proteolipid protein (the main component of myelin).  

The effectiveness of T2w, and especially its role in determining T1T2R, can expand the effectiveness of MRI, Dr. Zheng noted. “We’re excited about the possibility of T1T2R as a tool for mapping cortical myelin. Because we can calculate the T1T2R map with the routine T1w and T2w images, this makes T1T2R a possible new tool for myelin mapping.”  

This has great potential for measuring the progress of MS, Dr. Zheng said. “It’s important to be able to be able to identify cortical lesions via MRI because they are now part of the MS diagnostic criteria.” 

While all three MRI techniques were relatively accurate in detecting areas of demyelination, their specificity was somewhat limited. Dr. Zheng believes the reason for this is that conventional MRI may be more sensitive to changes in the brain other than demyelination. “This is why we need to improve our ability to use MRI in managing MS,” she said. “Higher resolution imaging and better processing will go a long way in identifying changes in the cortex in these patients.” 

This study was supported by the National Institute of Neurological Disorders and Stroke, part of the National Institutes of Health.