Grey matter atrophy impacts localized brain regions that are functionally connected in patients with multiple sclerosis (MS), according to a new study published in Clinical Radiology. The results may serve as a framework for developing imaging biomarkers.
Traditionally, MS has been connected to abnormalities involving white matter in the central nervous system; more recently, however, MS has been shown to involve grey matter (GM), wrote F. L. Chiang, University of Texas Health Science Center at San Antonio, and colleagues.
“Brain regions that are selectively vulnerable to GM atrophy have been shown to act as ‘nodes’ in functional networks; this forms the basis for the network degeneration hypothesis (NDH),” Chiang and colleagues added. “The goal of this study was to test the NDH in localized GM atrophy using coordinate-based meta-connectomic modelling techniques. It was hypothesized that in MS (1) GM atrophy would be regionally selective and (2) these affected regions would be connected functionally.”
The researchers performed a meta-analysis which included 33 studies consisting of 1,666 MS patients and 1,269 controls. All participants had coordinate-based results from voxel-based morphometry analysis showing GM atrophy. They performed mass univariate and multivariate coordinate-based meta-analyses to test their hypotheses.
Overall, Chiang et al. found localized GM atrophy in the thalamus, putamen, caudate, sensorimotor cortex, insula superior temporal gyrus and cingulate gyrus. Additionally, the team found “significant interregional functional co-activations.”
“In this two-stage meta-analysis in MS, both hypotheses were confirmed,” the authors wrote. “This study identified consistent, regionally selective neurodegenerative changes and characterized the inter-regional co-activations meta-analytically.”
Findings from this study can guide the future creation of “quantitative neuroimaging markers for diagnosis, evaluating disease progression and monitoring treatment response,” the authors wrote.
One limitation the group highlighted is a lack of consensus on how to best analyze connectivity. They also suggested future work should involve research into more sensitive imaging methods to overcome the limits of current T1-and T2-weighted techniques.
“Although conventional MRI methods provide valuable clinical information in vivo, more advanced techniques are necessary to improve standard-of-care imaging in MS and solidify our understanding of the neurodegenerative pathophysiology,” the researchers concluded.