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  • Functional Brain Patterns act as “Fingerprint” for MS Patients

    Researchers are using MRI to characterize individual functional brain networks in patients with multiple sclerosis. By Evonne Acevedo

    May 1, 2017

    MRI can help to map functional connectivity in the brains of patients with multiple sclerosis (MS) and those with clinically isolated syndrome (CIS), which carries a high risk of progressing to MS.

    “Similar to human fingerprints, patterns of functional brain networks are unique for each person, and thus characterizing individual functional brain networks is of great significance for understanding inter-subject variability in cognition and behavior,” said Jinhui Wang, PhD, an investigator at the Center for Cognition and Brain Disorders at Hangzhou Normal University in China.

    In a study in the February 2017 issue of Radiology, Dr. Wang’s team investigated functional brain networks of 34 patients with MS, 34 patients with CIS and 36 demographically-matched healthy controls. The researchers found a decrease in whole-brain network connectivity efficiency and regional connectivity in the patients with MS compared to healthy controls. They also discovered that impaired regional connectivity was already detectable in the patients with CIS.

    Dr. Wang explained that functional brain networks can be modelled as a collection of nodes linked by edges, with nodes representing brain regions and edges representing inter-regional statistical interdependence of regional time signals.

    The team employed resting-state functional MRI (fMRI), which Dr. Wang said offers advantages over conventional task fMRI studies that require participants to perform cognitive tasks.

    “Conventional task-activation studies typically have a poor signal-to-noise ratio because the task-evoked signal changes are often small relative to the noise,” Dr. Wang said. “The noise considered in task studies has two sources — true noise and spontaneous neural activity. The latter is dominant and the signal of interest in resting-state fMRI studies.”

    For that reason, resting-state fMRI studies have approximately three times higher signal-to-noise ratio than task-activation studies. Resting-state fMRI also facilitates more accurate data comparisons while making participation easier on patients.

    “This is crucial for clinical studies because many patients are not capable of accomplishing complicated tasks accurately due to their cognitive dysfunctions or physical impairments,” Dr. Wang said.

    In patients with CIS, whole-brain network efficiency remained largely intact, but the researchers observed regional network alterations.

    “Compared with healthy controls, patients with CIS exhibited significantly lower values of nodal local efficiency in the superior temporal parts of the bilateral temporal pole and the left rolandic operculum and the insula,” Dr. Wang explained.

    “Relative to healthy controls, the functional connectivity decreased to a lesser extent in both the amplitude and number for patients with CIS than those with MS, in spite of non-significant differences between the two groups,” Dr. Wang said. “This implies the potential of the disrupted functional connectivity observed here in the early intervention of MS.”

    Recent studies have shown that connectivity patterns can act as a “fingerprint” to accurately identify individuals and predict brain activity, Dr. Wang said. For patients with brain disorders, studies are also increasingly demonstrating that the functional connectome can provide biomarkers for individual diagnosis and prognosis.

    “For instance, we have demonstrated that baseline functional brain networks can predict short-term clinical outcomes after pharmacological therapy for patients with a major depressive disorder,” he said. “Accordingly, neuroimaging-based functional network mapping has great potential in guiding personalized therapeutic regimens.”

    Between-group differences in nodal local efficiency (A) and interregional functional connectivity (B). Four regions were detected to show decreased nodal local efficiency in patients with MS and CIS compared with the healthy controls (HCs) but non-significant differences were observed between the patient groups. For interregional functional connectivity, a distributed component was identified to show decreases in the patients with MS compared with the HCs. A similar but spatially more focal component was further observed for the CIS patients versus the HCs. (Radiology 2017;37;3:719-736) © RSNA 2017. All rights reserved. Printed with permission.

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